USING THE 2014 MINNESOTA TREE INSPECTOR PROGRAM STUDY MANUAL The materials included in this manua, and accompanying study links, provide all essential information needed to answer the questions contained in the 2014 Certified Minnesota Tree Inspector Exam. New materials include a “Best Planting Practices” section with links to videos and more pests and pathogens tha threaten Minnesota trees and forests. A “Section Review Quiz” was added at the end of many sections and topic areas. These quizzes focus on important section or topic points and, will ask many on the certification exam. “Supplemental Materials” are included in this manual. They are provided solely for individual study and reference. THESE ARE NOT MATERIALS COVERED IN THE 2014 TREE INSPECTOR EXAM. Your interest and participation in this program has been vital to its continued success in growth. Thank You.
Sean Peterson U of M, Forest Resources Program Coordinator Minnesota Tree Inspector Program
For a printable PDF version (in whole or by topic) follow this link or go to the “Resources” page @ www.mntreeinspector.com .
CONTENTS Sections and Topic Areas
Articles
Author(s)
Section 1: Program Overview, DNR Governance and Regulations Minnesota Tree Inspector Program: Program Overview and Timelines Minnesota DNR, 2007 Forest Health Statutes Section 2:Firewood Regulation and Identification
Sean Peterson, University of Minnesota, Dept. Forest Resources (U of M, F.R.) Minnesota Department of Natural Resources (DNR)
2007 Firewood & Forest Pest Statutes “What’s In That Wood Pile?”
Minnesota DNR Gary Johnson and Rebecca Koetter, U of M, F.R. Section Review Quiz: Firewood Identification and Regulations Section 3: Pests and Pathogens in Minnesota “How to Identify and Manage Dutch Elm Disease” “Managing Dutch Elm Disease”
U.S.D.A., Northwest Area David French, University of Minnesota Extension
Section Review Quiz: Dutch Elm Disease “Oak Wilt in Minnesota”
David French and Jennifer Juswik
“Root Graft Barriers for Oak Wilt Control”
Minnesota Department of Agriculture (MDA)
Section Review Quiz: Oak Wilt “Signs and Symptoms of Emerald Ash Borer” “Emerald Ash Borer in Minnesota”
Section Review Quiz: Emerald Ash Borer
Mary Wilson, MSU Extension Eric Rebek, Michigan State University Dept. of Entomology Jeffrey Hahn, University of Minnesota, Entomology
Section 4: Other Pests, Plants & Pathogens “Pest Alert”, Bur Oak Blight American and Oriental Bittersweet Identification “Pest Alert”: Forest Tent Caterpillar
U.S. Dept. Of Agriculture U.S. Geological Survey, Great Lakes Science Center U.S. Dept. Of Agriculture
Section Review Quiz: Other Pests, Plants and Problems Section 5: Best Planting Practices Video Links: Planting typical and atypical stock types, correction of less viable nursery stock, staking and stem protection
Peterson, U of M, F.R.
“Three Steps for Planting Trees and Shrubs”
Lauren Stuft U of M, F.R.
“All You Need to Know About Community Gravel Beds”, 2013 Edition (excerpt) “Buried Root Systems and Tree Health”
Peterson, Jacob Busiahn U of M, F.R. Johnson, U of M, F.R. Johnson and Eric North, U of M, F.R. Johnson, Mike Zin and Mark Shippe, U of M, Extension Publication Minnesota Department Of Transportation
“Strong Winds-Weak Trees-Lots of Debris” “Tough Trees and Shrubs for Tough Sites”
MnDOT Landscape Inspection Manual, 2013 Edition (excerpt) Section Review Quiz: Best Planting Practices
Reference List and links to supplemental materials and web resources. Section Review Quiz Answers
Minnesota Tree Inspector Program History & Overview: Implemented in 1974 in response to Dutch elm disease and oak wilt, and now broadened to include emerald ash borer as well as other invasives and diseases affecting Minnesota’s natural and urban landscapes, the Minnesota Tree Inspector Program has grown to serve hundreds of communities and is approaching 1,000 certified inspectors in 78 of Minnesota’s 87 counties (Oct. 2013). Inspectors must pass an exam where they demonstrate proficiency in Dutch elm disease, oak wilt management, emerald ash borer, tree identification, firewood identification, best planting practices, and shade tree management. To retain certification, tree inspectors must attend six hours of annual pre-approved trainings or events. Qualifying events are determined by the University of Minnesota A current list of qualifying events is found at www.mntreeinspector.com.
Certification FAQ's Why should I become certified? There are many reasons people choose to become certified. The most common are: Professional development. Maintain employment. Many tree care professionals, especially in the public sector (Park & Rec., S.W.C.D., public works employees, etc.) are required to have and maintain certification. • Seeking employment. In both the private and public sector, it is increasingly common for employers to require Tree Inspector • Certification as a prerequisite for a job interview. • •
How do I become certified? To become certified as a new tree inspector, you must pass an examination that measures knowledge in shade tree pest identification and management. Most exams are given at the end of “New Tree Inspector Certification Workshops” or; at the “Forest Pest First Detectors” workshop.. Study manuals available at www.mntreeinspector.com on the “Resources” page. New Tree Inspector Workshops are held twice a year in St. Paul. A person must receive a score of 70 percent or better to become certified. The workshop you attend, combined with your study packet, contain information so you can demonstrate the following qualifications:
• Ability to identify all native tree species common to your area with or without leaves, and all felled or downed trees with bark • • • •
intact. Knowledge and understanding of the biology of Minnesota's most common shade tree pests. Familiarity with symptoms of oak wilt and Dutch elm disease, and the ability to identify other problems affecting oaks and elms. Knowledge of proper sample collecting methods for disease diagnosis. Knowledge of the approved control methods for common tree pests.
How long is the Certified Tree Inspector certification valid? The Minnesota Department of Natural Resources (DNR) will mail your certificate upon passing the exam. You are certified from the day you pass the exam to Dec. 31 of the following year.
© 2014 Minnesota DNR, University of Minnesota
Minnesota Tree Inspector Program: Recertification FAQ How do I recertify? Tree inspectors must take one continuing education workshop every year by Dec. 31to receive a certificate for the following calendar year. Tree inspector recertification is valid for one calendar year (Jan. 1 through Dec. 31). Your certification will expire if you do not attend a recertification workshop. If you wish to be certified again, you must retake and pass the exam.
How do I recertify? A total of 6 hours is needed annually for recertification through a qualifying workshop or event. You can either attend one 6 hour session or two sessions that are at least 4 hours in length. Most events that qualify toward recertification can be found at www.mntreeinspector.comNo event or workshop with less than 4 hours in length will be considered toward your recertification. If seeking recertification other than at the Shade Tree Short Course or other University of Minnesota sponsored workshops is desired and meets the education criteria below, it could qualify for recertification. In this instance you must submit an event or workshop agenda to the Tree Inspector Certification Program Coordinator for review and approval; it is recommended you do this at least two weeks prior to an event. The Program Coordinator is Sean Peterson, e-mail pete77955@umn.edu or call 612-624-4261. Sample agendas at a workshop qualifying for recertification can focus on any of the following: • Biology of native or invasive plants, insects or disease pests, or disorders affecting shade trees • Identification of symptoms characteristic of new insect, plant, and disease problems affecting shade trees other than those of Dutch elm disease and oak wilt • Proper methods of collecting and submitting samples for possible new plant, insect, or disease diagnosis • Identification of invasive pest threats to Minnesota trees, including but not limited to gypsy moth, emerald ash borer, sudden oak death, Asian longhorned beetle and others as appropriate • Recognizing hazard trees (high, moderate, and low levels of risk associated with urban trees) • Minimizing decay, storm damage, and maintenance damage to landscape trees • Correcting structural defects in young trees • Planting practices • Diag n o sin g tree and shrub diseases, disorders or damage
How often must I recertify? Recertification is a yearly process. You must complete all 6 of your recertification hours by the expiration date printed on your Tree Inspector card. Recertification is valid until Dec. 31 of the following calendar year.
© 2014 Minnesota DNR , University of Minnesota
Minnesota Statutes Passed in 2007: DNR Forest Health Statutes with New Community Shade Tree and Forest Pest Definitions and Authorities
Although the statute repeals Agriculture 18G, it leaves intact the MDA authority to survey, contain, and eradicate invasive forest pests. Those authorities are described under 18G.01, 18G.04, 18G.12
SUMMARY of STATUTE EXEMPTIONS. Chapter 84D.14
Updates 84D to reflect changes in 18G
This chapter does not apply to: (1) pathogens and terrestrial arthropods regulated under sections 18G.01 to 18G.15; or (2) mammals and birds defined by statute as livestock.
Chapter 88.01
Adds a definition for community forests.
Subd. 27. Community forest. "Community forest" means public and private trees and associated plants occurring individually, in small groups, or under forest conditions within a municipality.
Chapter 88.79
Recognizes the importance of urban and community forestry by giving the DNR commissioner general authority to hire staff and provide technical assistance for the purpose of enhancing the sustainability of urban and community forest resources.
Subdivision 1. Employment of competent foresters; service to private owners. The commissioner of natural resources may employ competent foresters to furnish owners of forest lands within the state of Minnesota who own not more than 1,000 acres of forest land, forest management services consisting of: (1) advice in management and protection of timber, including written stewardship and forest management; (2) marking of timber to be cut; (3) measurement of products; (4) aid in marketing harvested products; (5) provision of tree-planting equipment; (6) advice in community forest management; and (7) such other services as the commissioner of natural resources deems necessary or advisable to promote maximum sustained yield of timber and other benefits upon such forest lands.
With regard to charges for DNR services, adds text to recognize the value of benefits other than timber that may be calculated in the transaction.
Subd. 2. Charge for service; receipts to special revenue fund. The commissioner of natural resources may charge the owner receiving such services such sums as the commissioner shall determine to be fair and reasonable. The charges must account for differences in the value of timber and other benefits. The receipts from such services shall be credited to the special revenue fund and are annually appropriated to the commissioner for the purposes specified in subdivision 1.
Chapter 88.82
MINNESOTA RELEAF PROGRAM.
Expands the forestry practices that can be cost-shared under the MN Releaf Program. Although this bill currently has no state funding associated with it, the changes are needed to better support sustainable urban and community forestry as partially funded by the USFS and administered through MN Releaf.
The Minnesota releaf program is established in the Department of Natural Resources to encourage, promote, and fund the inventory, planting, assessment, maintenance, improvement, protection, and restoration of trees and forest resources in this state to enhance community forest ecosystem health and sustainability as well as to reduce atmospheric carbon dioxide levels and promote energy conservation.
Chapter 89.001
Adds climate to the definition of forest resources in recognition of the benefits provided by trees in enhanced air quality and reduced urban heat island effects.
Subd. 8. Forest resources. "Forest resources" means those natural assets of forest lands, including timber and other forest crops; biological diversity; recreation; fish and wildlife habitat; wilderness; rare and distinctive flora and fauna; air; water; soil; climate; and educational, aesthetic, and historic values.
Updates the definition of forest pest.
Subd. 15. Forest pest. "Forest pest" means any vertebrate or invertebrate animal, plant pathogen, or plant that is determined by the commissioner to be harmful, injurious, or
Adds a parallel definition for shade tree pests. Separate definitions are needed because of specific references to forest pests in statute 89.039 that govern the Forest Management Investment Account.
Refers to the previous definition given for community forests under 84D.
Subd. 16. Shade tree pest. "Shade tree pest" means any vertebrate or invertebrate animal, plant pathogen, or plant that is determined by the commissioner to be harmful, injurious, or destructive to shade trees or community forests.
Subd. 17. Community forest. "Community forest" has the meaning given under section 88.01, subdivision 27.
Adds a definition for shade tree, originally taken from 18G.16
Subd. 18. Shade tree. "Shade tree" means a woody perennial grown primarily for aesthetic or environmental purposes.
Chapter 89.01
Clarifies both the need and the authority to develop best management practices to address actual and potential damage due to forest pests.
Subdivision 1. Best methods. The commissioner shall ascertain and observe the best methods of reforesting cutover and denuded lands, foresting waste lands, minimizing loss or damage of forest resources by fire, forest pests, or shade tree pests, administering forests on forestry principles, encouraging private owners to preserve and grow trees or timber for commercial or other purposes, and conserving the forests around the head waters of streams and on the watersheds of the state.
Specifies forest pest and shade tree pest protection as responsibilities of the DNR commissioner.
Subd. 2. General duties. The commissioner shall execute all rules pertaining to forestry and forest protection within the jurisdiction of the state; have charge of the work of protecting all forests and lands from fire, forest pests, and shade tree pests; shall investigate the origin of all forest fires; and prosecute all violators as provided by law; shall prepare and print for public distribution an abstract of the forest fire laws of Minnesota, together with such rules as may be formulated.
Adds text to better reflect the breadth of planning work done in cooperation with DNR’s partners.
Subd. 4. Forest plans. The commissioner shall cooperate with the several departments of the state and federal governments and with counties, towns, municipalities, corporations, or individuals in the preparation of plans for forest protection and management and planting or replacement of trees in wood lots and community forests or on timber tracts, using such influence as time will permit toward the establishment of scientific forestry principles in the management, protection, and promotion of the forest resources of the state.
Chapter 89.51
Updates statutes citations.
Subdivision 1. Applicability. For the purposes of sections 89.51 to 89.64 the terms described in this section have the meanings ascribed to them.
Corrects a previous typographical error and adds text to reflect the parallel definitions of forest and shade tree pests.
Subd. 6. Infestation. "Infestation" includes actual, potential, incipient, or emergent infestation or infection by forest pests or shade tree pests.
Chapter 89.52
Adds text to reflect the parallel definitions of forest and shade tree pests. Chapter 89.53
SURVEYS, INVESTIGATIONS.
The commissioner shall make surveys and investigations to determine the presence of infestations of forest pests or shade tree pests. For this purpose, duly designated representatives of the commissioner may enter at reasonable times on public and private lands to conduct the surveys and investigations.
CONTROL OF FOREST PESTS AND SHADE TREE PESTS
Adds shade tree pest control to the DNR’s current forest pest control responsibilities. This is the major transfer from the MDA. It transfers MDA’s 18G language where feasible and also incorporates shade tree pest control as a parallel activity to the DNR’s existing forest pestcontrol whenever possible.
Requires the DNR to specify what control measures will be applied in public notices.
Direct transfer from MDA. Chapter 89.54
Whereas the term “Control Area” was used in 18G, “Zone of Infestation” is used in 89.54 Section 21. This change provides consistency in the terminology for both forest and shade tree pests.
Subdivision 1. Commissioner's duties; notice of control measures. Whenever the commissioner finds that an area in the state is infested or threatened to be infested with forest pests or shade tree pests, the commissioner shall determine whether measures of control are needed, what control measures are to be applied, and the area over which the control measures shall be applied. The commissioner shall prescribe a proposed zone of infestation covering the area in which control measures are to be applied and shall publish notice of the proposal once a week, for two successive weeks in a newspaper having a general circulation in each county located in whole or in part in the proposed zone of infestation. Prescribing zones of infestation and prescribing measures of control are exempt from the rulemaking provisions of chapter 14 and section 14.386 does not apply.
Subd. 2. Notice requirements; public comment. The notice shall include a description of the boundaries of the proposed zone of infestation, the control measures to be applied, and a time and place where municipalities and owners of forest lands or shade trees in the zone may show cause orally or in writing why the zone and control measures should or should not be established. The commissioner shall consider any statements received in determining whether the zone shall be established and the control measures applied.
Subd. 3. Experimental programs. The commissioner may establish experimental programs for the control of forest pests or shade tree pests and for municipal reforestation.
ZONES OF INFESTATION, ESTABLISHMENT.
Upon the decision by the commissioner that the establishment of a zone of infestation is necessary, the commissioner shall make a written order establishing the zone, and upon making the order, the zone shall be established. Notice of the establishment of the zone shall thereupon be published in a newspaper having a general circulation in each county located in whole or in part in the proposed zone and posted on the Department of Natural Resources Web site.
Chapter 89.55
INFESTATION CONTROL, COSTS
Allows control of pathogens regardless of the vector that transmits them. Authorizes the commissioner to prevent spread of an established pest to uninfected areas of the state. Eliminates the term “timber” which is vague in meaning.
Upon the establishment of the zone of infestation, the commissioner may apply measures of infestation prevention and control on public and private forest and other lands within an infected zone and to any trees, plants, wood or wood products, or contaminated soil harboring or which may harbor the forest pests or shade tree pests. For this purpose, the duly authorized representatives of the commissioner are authorized to enter upon any lands, public or private within the zone. The commissioner may enter into agreements with owners of the lands in the zone covering the control work on their lands, and fixing the pro rata basis on which the cost of the work will be shared between the commissioner and the owner.
Chapter 89.551
APPROVED FIREWOOD REQUIRED
(a) After the commissioner issues an order under paragraph (b), a person may not possess firewood on land administered by the commissioner of natural resources unless the firewood:
(1) was obtained from a firewood distribution facility located on land administered by the commissioner; (2) was obtained from a firewood dealer who is selling firewood that is approved by the commissioner under paragraph (b); or (3) has been approved by the commissioner of natural resources under paragraph (b). (b) The commissioner of natural resources shall, by written order published in the State Register, approve firewood for possession on lands administered by the commissioner. The order is not subject to the rulemaking provisions of chapter 14 and section 14.386 does not apply. (c) A violation under this section is subject to confiscation of firewood and after May 1, 2008, confiscation and a $100 penalty. A firewood dealer shall be subject to confiscation and assessed a $100 penalty for each sale of firewood not approved under the provisions of this section and sold for use on land administered by the commissioner. (d) For the purposes of this section, "firewood" means any wood that is intended for use in a campfire, as defined in section 88.01, subdivision 25.
Chapter 89.56
Adds shade trees to those of “commercial timber purposes.�
Subdivision 1. Statement of expenses; cost to owners. At the end of each fiscal year and upon completion of the infestation control measures in any zone of infestation, the commissioner shall prepare a certified statement of expenses incurred in carrying out the measures, including expenses of owners covered by agreements entered into pursuant to section 89.55. The statement shall show the amount that the commissioner determines to be the commissioner's share of the expenses. The share of the commissioner may include funds and the value of other contributions made available by the federal government and other cooperators.
The balance of the costs shall constitute a charge on an acreage basis as provided herein against the owners of lands in the zone containing trees affected or likely to be affected by the forest pests or shade tree pests for which control measures were conducted. In fixing the rates at which charges shall be made against each owner, the commissioner shall consider the present commercial value of the trees on the land, the present and potential benefits to the owner from the application of the control measures, the cost of applying the measures to the land, and such other factors as in the discretion of the commissioner will enable determination of an equitable distribution of the cost to all owners. No charge shall be made against owners to the extent that they have individually or as members of a cooperative association contributed funds, supplies, or services pursuant to agreement under this section.
Adds shade trees to existing authority.
Chapter 89.57
Adds shade trees to existing authority. Chapter 89.58
Adds shade trees to existing authority. Chapter 89.59
Adds shade trees to existing authority.
Chapter 89.60
Changes citation to include transferred shade tree authority.
Subd. 3. Collection. The unpaid charges assessed under sections 89.51 to 89.64 and the actions of the commissioner on any protests filed pursuant to subdivision 2, shall be reported to the tax levying authority for the county in which the lands for which the charges are assessed are situated and shall be made a public record. Any charges finally determined to be due shall become a special assessment and shall be payable in the same manner and with the same interest and penalty charges and with the same procedure for collection as apply to ad valorem property taxes. Upon collection of the charges, the county treasurer shall forthwith cause the amounts thereof to be paid to the forest pest and shade tree pest control account created by section 89.58. Any unpaid charge or lien against the lands shall not be affected by the sale thereof or by dissolution of the zone of infestation.
DISSOLUTION OF ZONE INFESTATION.
Whenever the commissioner shall determine that forest pest or shade tree pest control work within an established zone of infestation is no longer necessary or feasible, the commissioner shall dissolve the zone.
FOREST PEST AND SHADE TREE PEST CONTROL ACCOUNT.
All money collected under the provisions of sections 89.51 to 89.64, together with such money as may be appropriated by the legislature or allocated by the Legislative Advisory Commission for the purposes of sections 89.51 to 89.64, and such money as may be contributed or paid by the federal government, or any other public or private agency, organization or individual, shall be deposited in the state treasury, to the credit of the forest pest and shade tree pest control account, which account is hereby created, and any moneys therein are appropriated to the commissioner for use in carrying out the purposes of sections 89.51 to 89.64.
COOPERATION.
The commissioner may cooperate with the United States or agencies thereof, other agencies of the state, county or municipal governments, agencies of neighboring states, or other public or private organizations or individuals and may accept such funds, equipment, supplies, or services from cooperators and others as the commissioner may provide in agreements with the United States or its agencies for matching of federal funds as required under laws of the United States relating to forest pests and shade tree pests.
DUTIES, RULES; COMMISSIONER.
The commissioner is authorized to employ personnel in accordance with the laws of this state, to procure necessary equipment, supplies, and service, to enter into contracts, to provide funds to any agency of the United States for work or services under sections 89.51 to 89.64, and to designate or appoint, as the commissioner's representatives, employees of cooperators, including employees of the United States or any agency thereof. The commissioner may prescribe rules for carrying out the purposes of this section.
Chapter 89.61
ACT SUPPLEMENTAL.
Changes citation to include transferred shade tree authority.
Provisions of sections 89.51 to 89.64 are supplementary to and not to be construed to repeal existing legislation.
Chapter 89.62
SHADE TREE PEST CONTROL; GRANT PROGRAM.
Subdivision 1. Grants. The commissioner may make grants to aid in the control of a shade tree pest. To be eligible, a grantee must have a pest control program approved by the commissioner that: (1) defines tree ownership and who is responsible for the costs associated with control measures; (2) defines the zone of infestation within which the control measures are to be applied; (3) includes a tree inspector certified under section 89.63 and having the authority to enter and inspect private lands; (4) has the means to enforce measures needed to limit the spread of shade tree pests; and (5) provides that grant money received will be deposited in a separate fund to be spent only for the purposes authorized by this section.
Subd. 2. Grant eligibility. The following are eligible for grants under this section:
The substantive part of the bill that transfers responsibility for grant making to control established shade tree pests from MDA to DNR. At the same time it modifies the program to make shade tree pest control activities parallel the long standing DNR programs for forest pest control.
(1) a home rule charter or statutory city or a town that exercises municipal powers under section 368.01 or any general or special law; (2) a special park district organized under chapter 398; (3) a special-purpose park and recreation board; (4) a soil and water conservation district; (5) a county; or (6) any other organization with the legal authority to enter into contractual agreements. Subd. 3. Rules; applicability to municipalities. The rules and procedures adopted under this section by the commissioner apply in a municipality unless the municipality adopts an ordinance determined by the commissioner to be more stringent than the rules and procedures of the commissioner. The rules and procedures of the commissioner or the municipality apply to all state agencies, special purpose districts, and metropolitan commissions as defined in section 473.121, subdivision 5a, that own or control land adjacent to or within a zone of infestation.
Chapter 89.63
Transfers this authority to DNR
CERTIFICATION OF TREE INSPECTORS.
(a) The governing body of a municipality may appoint a qualified tree inspector. Two or more municipalities may jointly appoint a tree inspector for the purpose of administering their respective pest control programs.
(b) Upon a determination by the commissioner that a candidate for the position of tree inspector is qualified, the commissioner shall issue a certificate of qualification to the tree inspector. The certificate is valid for one year. A person certified as a tree inspector by the commissioner may enter and inspect any public or private property that might harbor forest pests or shade tree pests. The commissioner shall offer an annual tree inspector certification workshop, upon completion of which participants are qualified as tree inspectors.
(c) The commissioner may suspend and, upon notice and hearing, decertify a tree inspector if the tree inspector fails to act competently or in the public interest in the performance of duties.
Chapter 89.64
Maintains MDA responsibility to control non-forest and invasive species.
EXEMPTIONS.
This chapter does not supersede the authority of the Department of Agriculture under chapter 18G.
Chapter 97A.205
ENFORCEMENT OFFICER POWERS.
An enforcement officer is authorized to: (1) execute and serve court issued warrants and processes relating to wild animals, wild rice, public waters, water pollution, conservation, and use of water, in the same manner as a sheriff; (2) enter any land to carry out the duties and functions of the division; (3) make investigations of violations of the game and fish laws; (4) take an affidavit, if it aids an investigation;
DNR enforcement officers are already empowered to enforce forest pest statutes. This section adds shade tree enforcement authority.
(5) arrest, without a warrant, a person who is detected in the actual violation of the game and fish laws, a provision of chapters 84, 84A, 84D, 85, 86A, 88 to 97C, 103E, 103F, 103G, sections 86B.001 to 86B.815, 89.51 to 89.64; or 609.66, subdivision 1, clauses (1), (2), (5), and ; and 609.68; and (6) take an arrested person before a court in the county where the offense was committed and
M a k e a c o m p l a i n t , n o t h i n g i n t h e s e c t i o n grants an enforcement officer any greater powers than other licensed peace officers.
FIREWOOD STATUTUE
Minnesota Statutes Passed in 2007: DNR Forest Health Statutes With New Community Shade Tree and Forest Pest Definitions and Authorities Chapter 89.551
APPROVED FIREWOOD REQUIRED (a) After the commissioner issues an order under paragraph (b), a person may not possess firewood on land administered by the commissioner of natural resources unless the firewood: (1) was obtained from a firewood distribution facility located on land administered by the commissioner; (2) was obtained from a firewood dealer who is selling firewood that is approved by the commissioner under paragraph (b); or (3) has been approved by the commissioner of natural resources under paragraph (b). (b) The commissioner of natural resources shall, by written order published in the State Register, approve firewood for possession on lands administered by the commissioner. The order is not subject to the rulemaking provisions of chapter 14 and section 14.386 does not apply. (c) A violation under this section is subject to confiscation of firewood and after May 1, 2008, confiscation and a $100 penalty. A firewood dealer shall be subject to confiscation and assessed a $100 penalty for each sale of firewood not approved under the provisions of this section and sold for use on land administered by the commissioner. (d) For the purposes of this section, "firewood" means any wood that is intended for use in a campfire, as defined in section 88.01, subdivision 25.
What’s In That Wood Pile? Identifying 3 groups of trees found in Minnesota wood piles By Gary Johnson and Rebecca Koetter - University of Minnesota, Department of Forest Resources - 2007
O ver view
Photo: Joseph O'Brien , USDA Forest Service
Figure 1: Oak tree infected with oak wilt
Photo: Penn. Dept. of Conservation & Natural Resources
Figure 3: Epicormic sprouting that occurs ~2 years after EAB infestation.
Firewood identification and quarantine has been one of the important tactics for managing oak wilt (OW) (Figure 1) and Dutch elm disease (DED) (Figure 2) in the Upper Midwest. Both of these fungal diseases can spread from standing dead and dying trees to healthy trees by insect vectors that are attracted to healthy trees, or fresh wounds in the case of oak wilt. Firewood from these trees may harbor insect vectors (DED) and promote conditions for production of fungal disease spores, which then may attract insect vectors to the fungus (OW). Thus, proper disposal or treatment of firewood from such diseased trees is extremely important. A relatively new devastating pest has been killing both urban and rural trees - the emerald ash borer (EAB) (Figure 3). All species of ash in the Fraxinus Photo: Dave Hanson, U of MN/Dept. of Forest Resources genus (green, black, white‌) are susceptible to this Figure 2: Elm tree infected with aggressive insect and once again, monitoring the Dutch Elm Disease movement and storage of firewood is critical to a complete management program. The main way the insect is spreading across the Upper Midwest is through transportation of ash firewood from trees that were killed by the insect and still harbor the borer. Elm (Ulmus species), oak (Quercus species), and ash (Fraxinus species) have unique wood grain and bark characteristics. Often it is combination of these characteristics that distinguish the exact species, and sometimes even odors and colors help. Very often, firewood piles have wood from both mature tree trunks as well as smaller, younger branches. The bark from tree trunks and tree branches of the same species look very different, so firewood identification from bark samples alone can be difficult and confusing. When bark is not enough to identify a piece of firewood, a close examination
of the end grain is necessary. A sharp knife or a single-blade razor, a 10x hand lens, and a liquid that will enhance the end grain all help the process. Shellac or boiled linseed oil are very effective end grain enhancers. Simply spray or brush the liquid on and the wood features (pores, rays, rings) become much more obvious. Even water works for a short time. ~~~~~~~Please note that seemingly different trees are referred to as groups throughout this fact sheet. Trees within these groups often have similarities among bark, wood, and leaves.~~~~~~~
Identif yi ng Firew ood: Types of End Grain There are three types of end grain used to identify firewood: ring porous, diffuse porous, and semi-ring porous. Of these three types only one type- ring porous- is characteristic of firewood that may house a harmful disease or insect in Minnesota. All species in the elm group, oak group and ash group have ring porous wood. Identification by end grain type may be difficult but with enough practice you will be able to distinguish ring porous wood from diffuse and semi-ring porous firewood.
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Identif yi ng Firew ood: Types of End Grain continued. Ring Porous. Within an annual growth ring there will be two regions– springwood (distinctly larger pores) and summerwood (distinctly smaller pores).
Diffuse Porous. Within an annual growth ring, springwood and summerwood are not distinctly different. Wood within an annual ring looks uniform. Photo : Peter Gillitzer, UMN/FR
Photo : Peter Gillitzer, UMN/FR
Figure 4: Group examples- oak, elm (including hackberry), and ash
Figure 5: Group examples- maple (including boxelder), birch, some poplars, basswood (a.k.a. linden), ironwood, buckeye, and black cherry
Elm group (including hackberry)
Figure 7: Leaves of elm group (including hackberry) have an oblique base.
Photo : Peter Gillitzer, UMN FR
Figure 6: Summerwood is wavy. Bark resembles bacon strips.
End grain– ring porous: Summerwood: small pores arranged in a wavy "tire track" pattern (Figure 6). Sapwood: white to tan colored. Heartwood: brown to reddish brown.
Note: Split sections of American and rock elm can have stringy, long grain wood (Figure 8).
Photo: Gary Johnson, UMN/FR
Figure 8: Stringy firewood characteristic of some elm species.
Bark: Cross-sections of American elm (Ulmus americana) and rock elm (Ulmus thomasii) bark have alternating bands of dark and light colored tissue that gives the appearance of “bacon strips” (Figure 6). Slippery elm (Ulmus rubra) does not have “bacon strip” bark. Exception: Hackberry, another member of the elm group, also has summerwood pores arranged in a wavy “tire track” pattern. However, it is not susceptible to DED. Also, its bark is characteristically corky and rough (Figure 9).
Photo: Dave Hanson, UMN/FR
Figure 9: Corky hackberry bark.
Page 3
Oak group Oak wilt affects all species of oak in Minnesota including the red oak group (Figure 10)- Northern red oak (Quercus rubra), Northern pin oak (Q. ellipsoidalis), Eastern pin oak (Q. palustris), and black oak (Q. velutina) and the white oak group (Figure 11)- white oak (Quercus alba), bur oak (Q. macrocarpa), and swamp white oak (Q. bicolor). Red oak group identification is most important because it is so susceptible to oak wilt and is the firewood most likely to have spore mats under the bark. Firewood from red oaks killed by oak wilt that has bark attached should be completely enclosed with black plastic for 12 months after tree death or until bark sloughs off.
Leaves: Red oak group
Photo: Dave Hanson, UMN/FR
Figure 10: Species of red oaks have pointed leaf margins.
Leaves: White oak group
Photo: Dave Hanson, UMN/FR
Figure 11: Species of white oaks have rounded leaf margins.
Sodium Nitrite (NaNO2) Test: Applying a 10% solution of sodium nitrite to the heartwood makes the natural light brown color of the red oak group heartwood only slightly darker (Figure 13). However, it turns the white oak group heartwood yellow-orange, then red-brown, and then dark green or purple to black (Figure 14).
Photo: Peter Gillitzer, UMN./FR
Figure 12: All species in the oak group have rays visible to the unaided eye. The growth ring includes one season of springwood and one of summerwood.
End grain– ring porous: Large wood rays are clearly visible to the naked eye. Within an annual growth ring, springwood has distinctly larger pores versus the smaller pores of summerwood (Figure 12).
Photo: Rebecca Koetter, UMN/FR
Figure 13: Red oak sprayed with NaNO2. Notice that wood color does not significantly change, not even with time lapse.
Photo: Rebecca Koetter, UMN/FR
Figure 14: White oak sprayed with NaNO2. Left: color change within seconds of application. Right: color change within minutes of application.
Notes: Freshly cut or split red oak has a very distinct odor– sweet or rancid. Heartwood of red oak is light reddish brown versus the light to dark brown heartwood of white oak.
Bark: Red oak group- The smaller diameter pieces of wood have flat, gray, and smooth bark. Larger diameter pieces have ridged and furrowed bark (Figure 15). Photo: Dave Hanson, UMN./FR
Figure 15: Mature bark of red oak (Q. rubra)
Bark: White oak group- Bark ranges from gray and platy (Q. alba) to deeply ridged and furrowed (Q. macrocarpa) (Figure 16).
Photo: Dave Hanson, UMN/FR
Figure 16: Mature bark of bur oak (Q. macrocarpa)
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Ash group End grain– ring porous: Within an annual growth ring, springwood has large obvious pores with an abrupt transition to summerwood that has very small pores (Figure 17). Bark: deeply furrowed, narrow ridges that are diamond to canoe shaped; ash gray to ash brown (Figure 18). Notes: Unlike the oak group, large visible rays are absent to the naked eye. Photo: Dave Hanson, UMN/FR
Figure 18: Mature bark of green ash
Glossar y
Photo: Peter Gillitzer, UMN/FR
Figure 17: Cross-section of green ash. Notice no obvious wood rays are present.
Diffuse porous- all pores are of similar size and can be found evenly distributed throughout the growth rings. Growth ring- contains two layers (springwood and summerwood) of cells resulting from one year of growth. Heartwood- nonliving and commonly dark-colored wood in which no water transport occurs; it is surrounded by sapwood. Ring porous- pore sizes found in springwood and summerwood are very different, forming conspicuous bands. Sapwood- outer part of the wood of stem or trunk, usually distinguished from the heartwood by its lighter color. Water transport takes place in sapwood. Springwood- large cells formed when the tree is rapidly growing and are usually visible without a hand lens. Summerwood- small to tiny cells formed during slower growth period of summer; not usually visible without a hand lens.
References Cooperative Extension Service. Is it red oak or white oak? Color Test will tell. University of Wisconsin Extension. G7FSRWO. (The sodium nitrite test- NaNO2) Core, H.A., Cote, W.A., and A.C. Day. 1979. Wood structure and identification. Syracuse University Press. Syracuse, New York. Hoadley, R.B. 2000. Understanding wood: a craftsman’s guide to wood technology. Tauton Press, Inc. Newtown, CT. Sharp, J.B. 1990. Wood identification: a manual for the non-professional. University of Tennessee. Agricultural Extension Service. Publication 1389. Raven, P.H., Evert, R.F. and S.E. Eichhorn. 1999. Biology of plants, 6th Edition. Worth Publishers, New York. White, M.S. 1980. Wood identification handbook: commercial woods of the Eastern United States. Colonial Hardwoods, Inc. Falls Church, VA.
Technical Advisors: Harlan Petersen, Extension Specialist and Assistant Professor, University Of Minnesota. Jennifer Juzwik– Northern Research Station, USDA Forest Service. Minnesota Shade Tree Advisory Committee Information Transfer subcommittee. For more information on oak wilt, Dutch elm disease, emerald ash borer and firewood identification visit: http://fr.cfans.umn.edu/extension. Search under Tree Health tab for Management Options and Urban Forestry tab for Firewood Identification.
1.
The westward spread of gypsy moths is primarily due to: A. the males, which can fly up to 10 miles per year. B. the larvae, which can be carried by wind up to 20 miles per year. C. the pupa, which can survive temperatures of minus 40 degrees F. D. the egg masses, attached to vehicles, trailers, lawn furniture, and camping equipment.
2.
It is illegal to bring firewood into a Minnesota State Park if the firewood was not from a DNR approved source. A. True. B. False.
3. It is illegal to bring firewood into a privately owned campground in Minnesota if the firewood was not from a DNR approved source. A. True. B. False. 4. After May 1, 2008, the illegal transport of firewood into a Minnesota DNR-administered land will be punishable by: A. imprisonment for 90 days. B. a penalty of $100. C. confiscation of the firewood. D. both b and c. E. none of the above.
5. It is legal to bring non-approved firewood into a Minnesota State Park campground as long as it contains no ash firewood. A. True. B. False.
*Answers for all “Section Quizzes� are located at the end of this manual.
Identify and Manage Dutch Elm Disease
Author Linda Haugen is a Plant Pathologist with the USDA Forest Service, Northeastern Area State and Private Forestry, St. Paul, Minnesota. Acknowledgments Thanks are extended to the many scientists who contributed suggestions and background material for this publication. Particular thanks for review of technical content go to: Mark Stennes, Consulting arborist, Top Notch Tree Care; Dr. Jay Stipes, Professor of Plant Pathology, Virginia Polytechnic Institute and State University; Dr. Eugene Smalley, Emeritus Professor of Plant Pathology, University of Wisconsin-Madison; Dr. Alden Townsend, Research Geneticist, USDA National Arboretum; James Sherald, Plant Pathologist, National Park Service; and Dr. Richard Campana, Emeritus Professor of Plant Pathology, University of Maine. Thanks for review of practical content are extended to Jim Hermann of Minneapolis Park and Recreation Board for review of the manuscript. Cover photo: Branch flagging symptoms from a single point of Dutch elm disease infection in crown of elm. (Photo courtesy of Dr. R. Jay Stipes.) The use of trade of firm names in this publication is for reader information and does not imply endorsement by the U.S. Department of Agriculture of any product or service.
Contents • • • • • • • •
Introduction Symptoms Distinguishing Dutch Elm Disease from other problems Disease Cycle of Dutch Elm Disease Managing Dutch Elm Disease Trees in Natural Stands and Wild Areas Deciding Which Management Practices to Use Bibliography
Introduction At one time, the American elm was considered to be an ideal street tree because it was graceful, long-lived, fast growing, and tolerant of compacted soils and air pollution. Then Dutch elm disease (DED) was introduced and began devastating the elm population. Estimates of DED losses of elm in communities and woodlands across the U.S. are staggering (figure 1). Because elm is so well-suited to urban environments, it continues to be a valued component of the urban forest despite the losses from DED. The challenge before us is to reduce the loss of remaining elms and to choose suitable replacement trees for the ones we cannot save.
Figure 1. This photo is all too typical of the devastation caused by Dutch elm disease. Once a tree in a row is infected, the disease can move through connected root systems to kill the entire row. (Photo courtesy of USDA Forest Service via Dr. R. Jay Stipes, Virginia Polytechnic Institute and State University)
This guide provides an update for urban foresters and tree care specialists with the latest information and management options available for Dutch elm disease.
Symptoms DED symptoms are the result of a fungus infecting the vascular (water conducting) system of the tree. Infection by the fungus results in clogging of vascular tissues, preventing water movement to the crown and causing visual symptoms as the tree wilts and dies. Foliage symptoms: Symptoms of DED begin as wilting of leaves and proceed to yellowing and browning. The pattern of symptom progression within the crown varies depending on where the fungus is introduced to the tree. If the fungus enters the tree through roots grafted to infected trees (see disease cycle section), the symptoms may begin in the lower crown on the side nearest the graft and the entire crown may be affected very rapidly. If infection begins in the upper crown, symptoms often first appear at the end of an individual branch (called "flagging") and progress downward in the crown (cover photo). Multiple branches may be individually infected, resulting in symptom development at several locations in the crown (figure 2). Symptoms begin in late spring or any time later during the growing season. However, if the tree was infected the previous year (and not detected), symptoms may first be observed in early spring. Symptoms may progress throughout the whole tree in a single season, or may take two or more years.
Figure 2. Branch death, or Flagging, at multiple locations in the crown of a diseased elm. (Photo courtesy of Dr. Steve Katovich,USDA Forest Service, St. Paul,MN.)
Vascular symptoms: Branches and stems of elms infected by the DED fungus typically develop dark streaks of discoloration. To detect discoloration, cut through and peel off the bark of a dying branch to expose the outer rings of wood. In newly infected d branches, brown streaks characteristically appear in the sapwood of the current year (figure 3). It is important to cut deeply into the wood or look at the branch in cross section for two reasons: (1) As the season progresses, the staining may be overlaid by unstained wood, and (2) if infection occurred in the previous year, the current sapwood may not be discolored. Figure 3. Brown streaking develops in sapwood of branches infected by Dutch elm disease fungus. Streaking is visible here (from left to right) in: (1) the newly formed sapwood, (2) spring sapwood overlaid by uninfected summer wood, and (3) is absent in an uninfected branch. (Photo courtesy of the America Phytopathological Society.)
Distinguishing Dutch Elm Disease From Other Problems Other pest problems commonly observed on elm include leaf spot diseases, which cause dark spots of dead tissue in the leaves, and elm leaf beetles, which eat holes in the leaves. These problems are easily distinguished from DED. Elm leaf beetles do not carry the Dutch elm disease fungus as elm bark beetles do. Two other diseases, elm yellows and bacterial leaf scorch, are more easily confused with DED. The symptoms of these diseases are compared to DED in table 1. Elm yellows. This disease, which is also called elm phloem necrosis, is caused by a phytoplasma (microscopic bacteria-like organism) which systemically infects the phloem tissue (inner bark) of the tree. It is a serious disease that causes tree death. Symptoms of elm yellows differ from DED in that the leaves turn yellow (not brown and wilted) and drop prematurely, and the symptoms appear in n the entire crown at the same time. The brown streaking which DED causes in the sapwood is absent, but the inner bark develops a tan discoloration and a characteristic wintergreen odor. Bacterial leaf scorch. This disease is caused by the bacterium Xylella fastidiosa, which infects and clogs the water conducting tissues of the tree. Infection by this bacterium causes a slow decline over many years. Once a tree is infected, symptoms recur annually. Symptoms of scorch are irregular browning along the leaf margin with a yellow border between green and scorched leaf tissue. Older leaves on a branch are affected first.
Disease Cycle of Dutch Elm Disease The biology, or "disease cycle," of DED depends upon the host, the fungus and the means by which the fungus moves into new host trees (figure 4).
Figure 4. The disease cycle of Dutch elm disease is closely linked to the life cycle of elm bark beetles.
(Artwork by Julie Martinez, Scientific Illustrator, St. Paul, MN)
The elm host. Native species of North American elms vary in their susceptibility to DED, even within species. American elm (Ulmus americana L.) is generally highly susceptible. Winged elm (U. alata Michx.), September elm (U. serotina Sarg.), slippery elm (U. rubra Muhl.), rock elm (U. thomasii Sarg.), and cedar elm (U. crassifolia Nutt.) range from susceptible to somewhat resistant. No native elms are immune to DED, but some individuals or cultivars have a higher tolerance (and thus may recover from or survive with infection) or resistance to DED. Many European and Asiatic elms are less susceptible than American elm. In addition to genetic factors present in some cultivars and species, physical factors affect tree susceptibility. These factors include time of year, climatic conditions (such as drought) and vitality of the tree. Water conducting elements are most susceptible to infection as they are being produced in the spring, thus elms are most susceptible to infection after earliest leafing out to midsummer. Trees are less susceptible under drought conditions. Vigorously growing trees are generally more susceptible than slower growing trees. The Dutch elm disease fungus. DED can be caused by either of two closely related species of fungi: Ophiostoma ulmi (Buism.) Nannf. (formerly called Ceratocystis ulmi) and Ophiostoma novo-ulmi Brasier. The latter, which is more aggressive in causing disease, was recently recognized as being a separate species. The DED fungus was first introduced to the U.S. on diseased elm logs from Europe prior to 1930. It is unknown when the more aggressive species became established in the U.S.; however it was possibly present as early as the 1940's- 1950's, and most likely caused much of the devastating mortality through the 1970's. The less aggressive species is becoming increasingly rare in nature, and the aggressive species is thought to be responsible for most of the current mortality. Although some local resurgence of DED has been observed, there is no evidence that it is due to a change in the pathogen. Localized resurgence is more likely due to the following: (1) a decrease in vigilance in monitoring and sanitation, (2) a build-up in populations of the insect vectors, or (3) ingrowth of susceptible host trees in the wild.
Spread by elm bark beetles. Overland spread of DED is closely linked to the life cycles of the native elm bark beetle (Hylurgopinus rufipes Eich.) and the smaller European elm bark beetle (Scolytus multistriatus Marsh.) (figure 5). Both beetles are attracted to stressed, dying or dead elm wood to complete the breeding stage of their life cycle. The adult beetles tunnel into the bark and lay their eggs in tunnels (called galleries) in the inner bark. The eggs hatch and the larvae feed in the inner bark and sapwood.
Figure 5. Overland spread of DED is closely tied to the life cycles of the Native elm bark beetle (top) and smaller European elm bark beetle (below). Note that the smaller European elm bark beetle is actually larger
The larvae mature into adults and emerge from the elm wood. If the DED fungus was present in the wood that the beetles infested, the fungus produces sticky spores in the beetle galleries. Spores of the DED fungus are eaten by or stick to the adult beetles as they than the native elm bark beetle. emerge from diseased trees. Adult beetles then visit healthy trees, (Artwork by Julie Martinez, Scientific Illustrator, St. Paul, MN) feed in twig crotches or branch inner bark, and introduce the fungus into or near severed wood vessels as they feed. The importance of the two bark beetle species as vectors of DED varies across the range of elms. In northern areas (northern parts of Minnesota, Wisconsin, Maine, New York and New England and most of Canada, where winter temperatures below -6째 F are common), the native elm bark beetle is the predominant vector. In other parts of North America, the smaller European elm bark beetle predominates. The life habits of the adults of the two species differ considerably, which has implications for management opportunities. These differences are described below. Smaller European elm bark beetles overwinter as larvae or adults within the stem of the tree where they hatched. They emerge as adults in spring to feed in twig crotches of healthy trees, where they can introduce spores of the DED fungus to the crown. High numbers of beetles frequently will feed in a single tree, resulting in multiple points of infection. The cycle is repeated when beetles then seek out diseased and dying wood to breed in throughout the growing season, completing two or more generations per year. They have the potential to rapidly build up high populations. Adult native elm bark beetles tunnel into the bark on the lower stems of healthy elms to overwinter. In spring they emerge to feed in the inner bark of elm branches and small stems before beginning their breeding cycle. They repeat their life cycle as previously described. They can transmit the DED fungus to healthy trees during the construction of overwintering sites in fall, or, more commonly, during feeding in spring. Once the DED fungus is introduced into the upper crown of healthy elms by bark beetles, it slowly moves downward, killing the
branch as it goes. Disease progression may occur rapidly, killing the tree by the end of the growing season, or may progress gradually over a period of two or more years. It is also possible that the tree may recover. The success and rate of progression wit hin the tree depends on tree size, time and location of infection in the tree, climatic conditions, and response of the host tree. Spread through grafted roots. Roots of the same or closely related tree species growing near each other often cross each other Figure 6. Where elms are in the soil and eventually fuse (become grafted) to each other. closely spaced, the Dutch elm disease fungus may move down The DED fungus can move from infected trees to adjacent trees a row of trees through grafted through these grafted roots. Infections that occur through root roots. Removing trees without grafts can spread very rapidly throughout the tree, as the fungus is breaking root grafts may not carried upward in the sapstream. Root graft spread of DED is a keep the fungus from moving very significant cause of tree death in urban areas where elms are into adjacent trees. (Photo courtesy of Dr. Joseph closely spaced (figure 6). O'Brien, USDA Forest Service, St. Paul, MN)
Managing Dutch Elm Disease DED is managed by interrupting the disease cycle. The most effective means of breaking the cycle is early and thorough sanitation to limit the population of the insects that transmit the fungus from tree to tree. Other useful means of affecting the disease c ycle include using insecticides to kill the insect vector, breaking root grafts between trees, injecting individual trees with fungicides to prevent or halt the fungus, out early infections, and planting DED tolerant or resistant elm cultivars or other tree speci es. Sanitation to reduce insect vectors. Many communities have been able to maintain a healthy population of mature elms through a vigilant program of identification and removal of diseased elms and (systematic of) weakened, dying or dead branches. Sanitation by prompt removal of diseased trees or branches reduces breeding sites for elm bark beetles and eliminates the source of the DED fungus. To be completely effective in interrupting the spread of the disease by elm bark beetles, stems and branches of DED infected trees must be de-barked, destroyed, or utilized before the bark beetles emerge. During the growing season, removal should be completed within 2 to 3 weeks of detection. During the dormant season, removal should be completed before April, when overwintering beetles may begin to emerge. Wood from infected trees can be destroyed by chipping, burning or burying. Wood may be retained for use as firewood or sawlog s if it is de-barked or covered from April 15th to October 15th with 4 to 6 mil plastic. The edges of the cover must be buried or sealed to the ground. If it is impossible to destroy all elm wood before the beetles emerge, the wood can be sprayed with a registered insecticide until disposal is possible. If insecticides are used, consider potential exposure to chemical residues when burning or handling the treated wood. Many communities have regulations on the removal of diseased elms and storage of elm firewood; make sure your activities comply with local regulations. Insecticides to kill insect vectors. In areas where the native elm bark beetle is the principal vector, sanitation may be augmented by applying a registered insecticide to the lower stem of healthy elms in late summer to early fall (i.e., at the first sign of autumn leaf color change) to kill adult beetles as they prepare overwintering sites. In areas where the smaller European elm bark beetle are common, spring feeding in twig crotches can be prevented by spraying the crowns of elm trees with a registered insecticide. However, this may not be a preferred treatment method because of the difficulty in getting thorough coverage of all susceptible twig t issue, the risk of insecticide drift and exposure, and high expense. Insecticide registrations and recommendations are frequently updated, and may vary considerably between states. Cooperative Extension Services at land grant colleges and certified arborists are able to provide current insecticide recommendations. Disruption of root grafts. Large trees within 25 to 50 feet of each other are likely to have root grafts. Breaking root grafts between infected trees and adjacent healthy trees is an important means to prevent movement of the fungus into the healthy trees. Roo t grafts should also be disrupted between the healthy tree adjacent to a diseased tree and the next healthy tree. It may even be desirable to sever grafts between very valuable trees before DED is observed in the vicinity, as a proactive measure. Root graft disruption should be completed before the infected trees are removed. Otherwise the transpirational pull from healthy trees will rapidly draw in the contents of diseased tree's root system when the vascular tension on the roots of the diseased tree is released by severing the stem. Root graft disruption can be accomplished by use of a vibratory plow or any trenching machine equipped with the longest blade available (preferably five-feet long, but at least three-feet long). Biocidal soil fumigants may also be used to kill root
grafts if no other alternatives are available. However, these chemicals are generally restricted use pesticides and may only be applied by professional pesticide applicators. In addition, biocidal chemicals may not be effective if soil temperatures are below 50 째F.
Injecting elms with fungicide. Certain fungicides, when properly injected, are effective in protecting elm trees from infection via beetle transmission. This treatment is expensive and must be repeated every one to three seasons, thus it is appropriate only for high value or historically important trees. The treatment itself also may pose risks to the health of the tree.
Figur Macroinjection of fungicide into the root flare of an elm (Photo courtesy of Mark Stennes, certified arborist, St. Paul, MN) In order to be effective, the fungicide must be present at adequate concentration at all potential points of infection. Thus the dosage and means of application are critical to success. The injection of chemical into root flares in large volumes of water (macro injection) provides thorough distribution of chemical in the crown (figure 7). Microinjection (injection of small volumes of concentrated chemical) is also an option, although it's efficacy compared to macroinjection has not been thoroughly researched. Preferably, injections should be done soon after the earliest leaves have fully expanded, but may be done from then to the end of the growing season. Label rates of concentration for chemical application are updated to reflect the most recent findings on effectivenes s; always follow the current label. Harmful effects of fungicide injection have sometimes been reported and include occasional leaf "scorching" or loss. Elms gen erally recover from this damage. Also, drilling injection holes results in wounding which, if repeated annually, may eventually result in significant discoloration and decay. Following fungicide injection with a flush of clean water can reduce damage to the cambium. Some chemicals are able to protect trees for up to three seasons, thus minimizing the frequency of treatments. Several fungicides are registered for injection to prevent DED infection. These chemicals vary in duration of protective effe cts, means of application, risk of damage to the tree, documentation of effectiveness, and cost. Certified arborists or Cooperative Extension Services at land grant colleges are able to provide current recommendations on product availability and effectiveness. Eradicating Dutch elm disease from newly infected trees. If a new crown infection of DED is detected early enough, there is opportunity to save a tree through , fungicide injection, or both. Eradicative treatment is not possible on trees that have become infected via root graft transmission. , which can literally eradicate the fungus from the tree by removing it, has a high probability of "saving" a newly infected tree that has less than 5% of its crown affected. To be a candidate for eradicative , the infection must be a new infection (not a residual infection from the previous season) and be present only in the upper crown (not yet present in the main stem). Since infection may be more advanced than symptoms indicate, it is important to peel off the bark of infected branches and locate the staining, which indicates the presence of the fungus. All infected branches should be removed at a branch fork at least 5 feet, and preferably 10 feet, below the last sign of streaking in the sapwood (figure 8). Whenever elm branches are pruned during the growing season, paint specifically formulated for use on trees should be applied to Figure 8. Eradicative of branches infected with DED may be prevent attraction of elm bark beetles to the wounded trees. effective if there is adequate length (5 to 10 feet) of clearwood (Painting tree wounds is generally not recommended, except to between the infected tissue and the remainder of the crown, or prevent disease transmission in oaks and elms.) if the tree has been properly treated with fungicide. (Artwork courtesy of Jim Lockyer, USDA Forest Service, Radnor, PA) is more likely to be effective if augmented by systemic injection of fungicides. Proper use of fungicides eliminates the need to eradicate all infected tissues from the tree, although all dead branches should eventually be removed. Whereas alone is not effective against residual infections, fungicide injection may be. If fungicides are used, they should be injected prior to removal of diseased branches. The keys to successful eradicative treatment are early detection and prompt treatment.
Planting Dutch Elm Disease resistant or tolerant trees. Planting trees with resistance or tolerance to DED is a valid management option. However, selecting only a few cultivars limits the genetic variability of the population. This could lead to increased risk of widespread losses if these cultivars are found to be susceptible to tree health problems such as poor adaptation to site, air pollution, other elm pests or pathogens (such as elm yellows or elm leaf beetle) or even other strains of DED which may eventually devel op. Thus it is prudent to plant a mixture of suitable cultivars of as many elm genotypes as possible. Santamour and Bentz (1995) recently published a checklist and brief description of elm cultivars in North America. The only true American elms on that list that are commercially available and have strong evidence of DED tolerance or resistance are the Princeton Elm, the American Liberty "multi-clone," and Independence, which is one of the cultivars in the American Liberty multi-clone. Two additional American elms, Valley Forge and New Harmony, were released by the USDA National Arboretum since the Santamour and Bentz listing was prepared. These two cultivars, which exhibit high tolerance to DED, should be available through retail nurseries by 2001.
Figure 9. Cultivars of elm selected for resistance to DED are available. This selection of Ulmus japonica demonstrates the potential these elms have as landscape trees. (Photo courtesy of Dr. Eugene Smalley, University of Wisconsin-Madison)
Besides true American elms, there are many other hybrid elm crosses and species of elm that have high tolerance or resistance to DED. Several of these have attractive form, are well suited to urban environments, and are readily available (figure 9). Many of these are listed and described by Santamour and Bentz (1995) in the previously mentioned checklist. In addition to careful selection of the tree species and cultivar, location and spacing are also important to reduce losses from DED. When selecting landscape trees and their locations, plant a mixture of tree species appropriate to the site. In addition to the species diversity, consider spacing of the trees. Future problems with root grafts can be avoided by carefully selecting planting location and maximizing tree species diversity.
Trees in Natural Stands or Wild Areas Infected elms in wild areas and natural stands that are within or near urban areas often serve as a reservoir of elm bark beetles and DED fungus to infect high value landscape trees. Management is necessary in order to protect urban elms. The most effective management option to reduce both the bark beetle vectors and the DED fungus is sanitation to promptly remove stressed, dead and dying elms as previously described. However, this intensity of treatment is often not feasible. A "trap tree" method was developed in the 1980's to more cost effectively reduce populations of elm bark beetles. Under this method, DED infected elms which are still living are treated with an herbicide that kills the tree quickly and promotes rapid drying out of the bark. The bark beetles are attracted to the dying trees, but the rapidly drying bark is unsuitable for them to complete their lifecycle, and the bark beetle populations are reduced. However, treated trees may then become hazard trees with high risk of falling an d causing personal injury or property damage. Another option in wild areas or natural stands, other than accepting losses from DED, is to eliminate all elms and manage for alternative species. However, it is often desirable to retain elms for biodiversity, aesthetic, economic, or other reasons
Deciding Which Management Practices to Use Different management strategies will be applicable depending on whether you are working with a community program or trying to protect individual trees. In a community program, the objective will be to protect a population of elms. Individual landowners, however, may have no control over what neighbors do with their elms but may want to protect or save their own trees. The amou nt of money an individual or community is able to spend will also vary. Where you have no control over the management of surrounding trees, the only options available are treatments to protect or save individual trees. Good sanitation practices and disruption of root grafts are necessary on individual properties, but these p ractices alone will not protect a tree from disease transmission by bark beetles from other properties. Preventive fungicide injection, eradicative and fungicide injection, and insecticide treatment are generally the only options available for individual trees. In a community program, resources to spend on individual trees may be low, but there is more opportunity to manage populations of elms. Where there are continuous elms, root graft disruption is essential to halt the spread. Sanitation is key to reducing b eetle and DED populations, and is effective. Community ordinances can be established to encourage prompt removal of diseased trees and
prevent the storage of elm wood with bark intact. Education will help citizens understand the importance and benefits of work ing together to manage DED. As resources allow, preventive treatment, eradicative treatment and insecticides can be used to augment a program. If you are working with a community with a significant elm resource, become familiar with the literature listed belo w and with what has worked well in other communities. The impact of DED on our urban forests has been massive. Despite the losses, elms should and will continue to be a component of many urban forests. We have an opportunity to consider what trees will compose the future urban forest, and we can learn from the past. Landowners and communities can and should choose carefully what types of trees to plant and where to plant them.
Bibliography • • • • • • • • • • • • •
Allison, J. R., and G. F. Gregory. 1979. How to Save Dutch Elm Diseased Trees by . USDA FS publication NA-GR-9. Ascerno, M. E., and R. P. Wawrzynski. 1993. Native Elm Bark Beetle Control. Minnesota Extension Service Publication FS-1420-GO. Becker, H. 1996. New American Elms Restore Stately Trees. 1996. Agricultural Research 44 (7):4-8. Brasier, C. M. 1991. Ophiostoma novo-ulmi sp. nov., Causative Agent of Current Dutch Elm Disease Pandemics. Mycopathologia 115:151-161. Gibson, L. P., A. R. Hastings, and L. A. LaMadeleine. 1981. How To Differentiate Dutch Elm Disease From Elm Phloem Necrosis. USDA-FS publication NA-FB/P-11. Hanish, M. A., H. D. Brown, and E. A. Brown (Eds.). 1983. Dutch Elm Disease Management Guide. USDA-FS and USDA Extension Service, Bulletin One. Lanier, G. N. 1988. Therapy for Dutch Elm Disease. Journal of Arboriculture 14(9):229-232. Lanier, G. N. 1989. Trap Trees for Control of Dutch Elm Disease. Journal of Arboriculture 15(5):105 -111. National Park Service. 1993. Bacterial Leaf Scorch of Landscape Trees. Center for Urban Ecology Information Bulletin. Santamour, Frank S., Jr., and Susan E. Bentz. 1995. Updated Checklist of Elm (Ulmus) Cultivars for Use in North America. Journal of Arboriculture 21 (3):122-131. Schreiber, R. R., and J. W. Peacock. 1979. Dutch Elm Disease and Its Control. USDA-FS Agriculture Information Bulletin No. 193. Stennes, M. A., and D. W. French. 1987. Distribution and Retention of Thiabendazole Hypophosphite and Carbendazim Phosphate Injected into Mature American Elms. Phytopathology 77:707-712. Stipes, R. J., and R. J. Campana, eds. 1981. Compendium of Elm Diseases. Published by the American Phytopathological Society. 96 pp.
Northeastern Area - State & Private Forestry Offices: Headquarters Northeastern Area State & Private Forestry USDA Forest Service 100 Matsonford Road 5 Radnor Corporate Center, Suite 200 Radnor, PA 19087-8775 Durham Field Office Northeastern Area State & Private Forestry USDA Forest Service Louis C. Wyman Forest Sciences Laboratory P.O. Box 640 Durham, NH 03824-9799 Morgantown Field Office Northeastern Area State & Private Forestry USDA Forest Service 180 Canfield Street Morgantown, WV 26505-3101 St. Paul Field Office Northeastern Area State & Private Forestry USDA Forest Service 1993 Folwell Avenue St. Paul, MN 55108-1099
Pesticide Precautionary Statement: Pesticides used improperly can be injurious to humans, animals, and plants. Follow label directions and heed all precautions on the labels. Store all pesticides in original containers, out of reach of children and foodstuffs. Apply pesticides selectively and carefully. Do not apply a pesticide when there is danger of drift to other areas. After handling a pesticide, do not eat, drink or smoke until you have washed. Dispose of empty pesticide containers properly. It is difficult to remove all traces of a herbicide (weed killer) from equipment. Therefore, to prevent injury to desirable plants do not use the same equipment for insecticides that you use for herbicides. NOTE: Some States have restrictions on the use of certain pesticides. Check your State and local regulations. Also, because registrations of pesticides are under constant review by the Federal Environmental Protection Agency, consult your county agricultural agent or State extension specialist to be sure the intended use is still registered.
Management of Dutch elm disease University of Minnesota Extension, David French
People proposing alternatives to sanitation were failing to understand the basic biology underlying the spread of the Dutch elm disease fungus From the very beginning of the impact of Dutch elm disease in the United States, professionals (i.e. scientists) and amateurs have competed in the search for a magic cure. Miraculous cures have been publicized to the extent that much of the “tried and true” basics of dealing with the disease have been shoved aside and even ridiculed. The unfortunate truth has been repeatedly supported by the failures of these “miracle” cures; the recommended control measures which are effective can be accomplished only with hard work and money.
No Magic Bullets People continue to search for that magic compound which will cure even diseased trees completely colonized by the fungus. Tremendous sums of money have been spent on fake cures, treatments which were known by those knowledgeable about tree diseases to be of no value. Often these cures, some of which receive national front page news coverage, are proposed by people who have little or no understanding of the fungus and the disease. Promotions by non-pathologists are not only publicized but are often also financially supported by the public. The major attention that these magic cures often receive is to the detriment of continuing education of the public on the proven control program. Not only is money often spent foolishly but the treated trees are lost as well. Despite all the efforts expended searching for an exciting new effective technique for controlling Dutch elm disease, the basic approach, known for years, remains the best. The simple answer to the control of Dutch elm disease is sanitation. Sanitation includes detection and destruction of all dead and dying elm trees, be they American, red, Siberian, or any kind. The notion that Siberian elms are resistant, which they are, and thus do not serve as sources of infested beetles is nonsense. The idea that every tree had to be diagnosed in the laboratory before it could be condemned was expensive, delaying, and led to further spread of the fungus. The “pressures” brought to bear on behalf of some elms, because of their prominence or their ownership by a prominent citizen, were also disastrous to neighboring elms. Sanitation programs were constantly being blocked and slowed by individuals who proclaimed to be concerned about our environment. Sanitation was further encumbered by the well-meaning Pollution Control Agency which prohibited burning, despite that being the most expeditious way to dispose of beetles and beetle environments. The efforts to slow Dutch elm disease would have fared much better and cost much less if burning had been allowed. Random uncontrolled burning was not what was sought. Supervised burning in prescribed locations would have provided great advantages to those fighting Dutch elm disease and
any resulting pollution could have been considered a small price to pay. The permissible thousands of fireplace fires in a single evening in Minnesota’s cities have far more impact on the environment than would have been created with the few fires that were foolishly prevented from being used to burn elm refuse piles. One of the major metropolitan elm disposal sites was fortunate to have accidently gotten around that burning ban. It was a site designed to promote the utilization of the elm wood from removed trees. Logs, branches, and brush poured into the site in conformance with magnificent plans to salvage the quality logs for use in a variety of products. Unfortunately, the amateur managers of the operation found themselves inundated in acres and acres of elm debris with more coming faster than they could manage. At one point their equipment couldn’t even move when it was in running order. Fortunately, on a day when the wind was blowing away from St. Paul and weather conditions were otherwise favorable, a fire started accidently. What would have cost millions of dollars and taken too long for the operators of the site to process, was quickly gone. The mayor of St. Paul and the city’s fire chief apparently decided it was safe to let the fire burn and better to save the money that would have been needed to put it out and to haul the debris to another location. The fire, which injured no one and had little impact on the environment, saved a lot of money. It was hard on bark beetles as well.
Egg-laying galleries of the European elm bark beetle have a characteristic but macabre appearence. They run parallel to the grain of the tree, with the larval feeding tunnels at right angles to the main gallery. The beetle overwinters as larvae and emerges as an adult around June. A second generation can be produced by these adults in late summer or early fall, and in some years weather can permit even a third generation to be produced.
People proposing alternatives to sanitation were failing to understand the basic biology underlying the spread of the Dutch elm disease fungus. The fungus spores carried by the two beetle carriers of Ceratocystis ulmi are spores produced in the insect galleries and the fungus is introduced to the galleries by the female beetles as they lay eggs. Thus it made little difference whether a tree died of Dutch elm disease or was killed by an automobile, a girdling chain or winter injury. Any dead or dying elm could harbor beetles and the fungus.
In the early stages of the control programs the requirement that laboratory tests confirm that an elm tree had Dutch elm disease delayed removal of hazardous trees. In some cases the lab diagnosis was a month or more late. On other occasions the samples from a suspected tree were inadequate, and though the tree was infected the fungus was not isolated. Those trees remained to endanger all elms in their vicinities. Laboratory confirmation was not necessary because Dutch elm disease can be diagnosed accurately in the field. Sanitation, in addition to detection and tree removal included separation of roots between infected and healthy trees, a technique often referred to as root barriers. With all the effort put into searching for a cure, practically nothing was done to develop a method of preventing movement of the fungus through common root systems. In some Minnesota communities, circumstantial evidence suggested that as many as 88 percent of all new cases of Dutch elm disease resulted from invasion through common root systems. The only known technique for disrupting these common root systems in cities was with the soil sterilant SMDC, but this method has not been well researched and doesn’t always work.
One major Minnesota city discontinued placing barrier chemicals around diseased trees when a study showed that their techniques were ineffective. They were ineffective because they were improperly placing the barrier, with the chemical applied only from curb to sidewalk. The roots of the boulevard elm trees extended much farther and were actually fused in the front yards where no barriers were placed. Even with barriers placed all around the diseased tree, they sometimes failed because the roots were not killed at all the points of application or because the fungus had already moved into the adjacent tree. Mechanical barriers are not a reasonable solution because of buried utilities. An important fact is that an elm infected through its roots can not be saved, but a beetle inoculated tree can be, through selective , if detected early enough. This other form of sanitation, , can be practiced only in a small percentage of cases. Aside from cost, the major objections to using this approach on public property is that it is extremely difficult for city foresters to monitor individual trees, especially when losing thousands of trees per year. It is a viable approach, however, and elms can be saved very easily by .
Selective , although expensive and labor intensive, can effectively extend the lives of some infected elms. Many of the successful chemical interventions may, in fact, be attributed as much to accompanying as to the use of the chemicals.
In University of Minnesota studies, over 95 percent of the diseased elms pruned experimentally have been saved. The technique prevents the fungus from entering the main stem and in turn the roots of that and neighboring trees. Many of the elms supposedly saved by injecting chemicals were probably actually saved by , which is part of the recommendation in chemically treating diseased trees.
Additional control measures do exist, but all are secondary to sanitation. When DDT could be used, it did provide some additional protection to a population of elms. Meth-oxychlor, one alternative to DDT, does not persist on foliage branches and must be applied in the spring when weather conditions often limit spraying operations. It has not been part of control programs in Minnesota as it is not effective enough to justify the expense. Many people also objected to having their houses, cars, yards and children sprayed. Cities that had such programs abandoned them.
Systemic Treatments There is a long history of systemic chemical treatments for Dutch elm disease, some directed at the elm bark beetle, but most directed at the fungus pathogen. The earliest systematic attempts were at the Connecticut Agricultural Experiment Station at New Haven in the 1940s. Effective systemic fungicides came along quite late in the epidemic. After some unsatisfactory results, research in Wisconsin and Minnesota finally determined that Arbotect is effective when used in sufficient amounts and when properly injected. Initially the insoluble form of benomyl was announced as an effective fungicide but its results were not impressive. Several publications developed by extension services described its use: the requirement for rapid distribution, the need for pressure equipment, and the technique for solubilizing the fungicide with lactic acid. Later benomyl was
solubilized with phosphoric acid and the latter material, the most promising of this series, Lignasan BLP, was labeled for control of Dutch elm disease. Arbotect came a bit later. Despite their efficacy for the control of Dutch elm disease, both Lignasan and Arbotect were labeled at rates far below what was needed for effective treatment, one-sixth the needed amount of Lignasan and one-third the amount of Arbotect. Initial injections were in the main stem above ground and later through severed roots. Best results were obtained by below grade or root flare injections which could protect elms for two years, and possibly even into a third season. Root flare injections have resulted in far better distribution of the chemical within the tree. The products currently labeled and used in the United States are water soluble acid salts of two benzimidazole compounds developed in the 1970s. Measured in terms of long-term prophylactic effectiveness in the tree, Arbotect 20-S (thiabendazole-hypophosphite) is currently the product of choice by the professional tree care industry. The product also has a therapeutic effectiveness if the fungus infection is not systemic, the highest label rate is delivered uniformly to all parts of the tree, and the symptomatic parts of the tree are subsequently removed. Current research at the University of Minnesota and Virginia Tech with a relatively new fungicide, called Alamo (propiconazole), although too preliminary to report, suggests that the product may be effective as a therapeutic treatment for diseased elms. Prophylactically, the product is completely effective against overland transmission in mature trees, at least for the short term (one season). Despite this progress on the chemical front, the economics of fungicide injection are entirely against the process, except for trees of high value. At more than $10 per inch of tree diameter (measured at at a height 54 inches above ground) it is expensive and certainly not logical for entire populations of trees. Injection will also not work in elms infected through the roots or when the fungus has already become established in the main stem. It is unfortunate that the majority of elms injected with system fungicides were improperly treated. Not only were the procedures a waste of money, but many homeowners, having invested several hundred dollars on the process to save their trees, argued that their elms should not be removed even though they constituted a hazard. The fungus and beetles profited as a result and the sanitation program lost ground. While systemic fungicide injection was of some value when properly administered, there were many other proposed cures for Dutch elm disease which, in spite of newspaper stories and self supporting statements, were of no value. There have, in fact, been well over 500, and possibly as many as 1,000 suggested cures for Dutch elm disease. Often people became unbelievably enthusiastic before any substantive evidence on a treatment’s effectiveness became available. Many elms have been treated with substances never even approved as non-hazardous by the Environmental Protection Agency. Many which have had EPA approval, have erroneously promoted the impression that EPA approval also means that a proposed fungicide actually works as advertised.
The EPA has always passed approval only on whether a compound is hazardous. The losers in these affairs have been the tree owners, paying out good money while still losing their trees. Another negative attached to the proliferation of unproven and ineffective treatments has been how those failures delayed the introduction of an effective chemical control. Research at the Sault St. Marie Laboratory in Canada found that Dursban (chlorpyrifos) was effective in reducing populations of the native elm bark beetle, which is the primary vector in northern Minnesota and much of Canada.2 But even with that evidence, it was several years before the use of Dursban was recommended in Minnesota. It has since become an important part of a control program, especially for northern Minnesota. 2
Gardiner, L.M. and Webb, D.P., 1980. Tests of chlorpyrifos for control of the North American elm bark beetle (Hylurgopinus rufipes Eichh). Department of the Environment, Canadian Forest Service, Sault St. Marie Report O–X–311.
Injection of dozens of biological and chemical compounds have been proposed as magic cures for Dutch elm disease. Several have been tried by researchers at the University of Minnesota, on the university's own trees. While a few of the compounds produce some degree of control, the overwhelming majority have been found worthless. Some can even be dangerous to the tree or the individual handling it.
The Future for Elms in Minnesota Our tendency has been to acquiesce to ease and convenience, which means we’ve planted easily grown, easily transplanted species Minnesota has not lost all of its elms since Dutch elm disease was first found in the state more than 30 years ago. While it is likely that many elms in forested areas of the state will be lost, including those of any substantial size, elms are a tenacious species and will always be with us. We just won’t have as many of the large specimens. The cities, however, face a different scenario, and any community that has good judgment will be able to keep many of its elms. A reasonable program of management can continue to maintain low losses and preserve a substantial portion of our shade tree elms. The management program is a wise investment because the absence of any effort to stop Dutch elm disease will result in dead trees which still must be removed. An argument can be made that a community actually saves money by keeping the elms it has for as long as it is able. Cities should appreciate that it takes decades for newly planted replacement trees to reach the stature and beauty of our existing residual elms. And the new trees will have their own problems, including susceptibility to their own diseases. Finally, for the very reason that so many elms were planted in the first place, we have to acknowledge that few other tree species are as beautiful and acceptable in as many respects for a shade tree. The choice of replacement trees is surprising in some respects. It’s understandable that we are planting more ash (26 percent) trees than any other single species because this tree is cheap to produce, easily transplanted, and, when young, reasonably attractive. But, older ash are not so attractive; they lose their leaves early in fall and are late producing leaves in spring. Some varieties of ash have had a high rate of mortality, and we now have two serious diseases of ash to contend with, ash yellows and Verticillium wilt. Another 38 percent of our new replacement trees are exotics which are not entirely suited for this part of the country. They are often prone to disease and insect problems. Why plant untested exotics when there are dozens of native species? The answer in part is that Minnesotans are not growing all of their own trees. A high proportion are being shipped in from other parts of the country. Even species native to Minnesota are not necessarily satisfactory if the seed from which they are grown comes from a distant tree. Red maples, for example, grow over much of the eastern United States, from Maine to Florida. But maples evolved and adapted to Florida are not likely to survive Minnesota’s climate. Other species that are being planted also have their own disease problems. Potentially, up to 20 percent of the honey locusts being planted can be infected by a lethal canker disease.
Why not resistant trees? Nothing has been said about resistant varieties of elms. When Dutch elm disease was causing tremendous losses in Minnesota in the 1970s was not the time to develop resistant elms, a process which takes years. The Dutch have been at it for six decades with only minimal success. They are still searching for that elm they need. Minnesota’s reforestry recommendations were based on planting trees which we know are resistant to Dutch elm disease. These include maples, hackberries, oaks, and birches to mention a few. There was no question about these trees being resistant to Dutch elm disease and they were suited to our climate.
Elm’s of any variety do little more than harbor the fungus and the beetles which spread it. The only appropriate use for so-called “resistant” varieties may be as firewood or mulch chips.
The resistant elms which were available in the early years of the Dutch elm disease epidemic, were exactly that, resistant but not immune. More important they were both not well suited to Minnesota and not comparable to the native elms in stature and beauty. Siberian and Chinese elms have resistance to Dutch elm disease fungus but are undesirable species because they are subject to winter injury. A not entirely facetious recommendation by this author has been that these trees be pruned at the ground line. It is not an uncommon scene in Minnesota to see rows and rows of dying Siberian elms which had been planted as windbreaks along roads and around farmers’ fields. Once established they can become a problem because of their heavy seeding habit.
Now is the time to choose carefully and wisely as we select the tree species we plant to renew our urban forests. Thus far this has not been done. Our tendency has been to acquiesce to ease and convenience, the translation of which means we’ve planted easily grown, easily transplanted species. Unfortunately this has led to planting too many ash trees, too many honey locusts, and too many little leaf lindens. There are other choices.
Is there a place for the elm in the future? The answer is a very definite yes. There are resistant elms more recently developed which have more desirable characteristics and these are now being evaluated in Minnesota. We should consider keeping the American elm in our landscape. As Dutch elm disease becomes less abundant, and possibly if the nonaggressive strain becomes more common (in 1977 only 8 percent of 1,124 isolates were nonaggressive), the American elm might be replanted in some locations. It should never be planted as abundantly as was done by our forefathers, but it should be a part of our landscape plans
1.
Dutch elm disease (DED) is caused by: A. the European elm bark beetle, Scolytus multistriatus. B. the fungus, Verticillium albo-atrum. C. the fungus, Ophiostoma ulmi. D. root grafts.
2. The spread of Dutch elm disease is primarily caused by: A. elm leaf beetles. B. elm bark aphids. C. elm bark beetles. D. all of the above. 3. Early-season symptoms of Dutch elm disease from the year before can be confused with: A. leaf miner and leaf beetle feeding damage. B. defoliation caused by the cankerworm. C. heavy seed production. D. all of the above. 4. During the growing season, elm trees should be inspected for Dutch elm disease symptoms by the following approximate dates: A. at least once, prior to June 1. B. at least twice: by June 15 and by September 15. C. at least three times: by June 15, July 15, and August 15. D. at least four times: by April 15, June 15, July 15, and August 15. 5. Bark-intact elm wood can be rendered pest-risk free by: A. chipping, debarking, burning, or burying. B. stockpiling the wood at the nearest approved utilization site. C. storing in a garage. D. all of the above.
*Answers for all “Section Quizzes� are located at the end of this manual.
Oak Wilt in Minnesota David W French Jennifer Juzwik
Copyright Š 2002 Regents of the University of Minnesota. All rights reserved.
Oak wilt, caused by a fungus Ceratocystis fagacearum, is responsible for killing large numbers of oaks annually in Minnesota. Oaks are undoubtedly the most valuable and plentiful of our shade trees. In contrast to Dutch elm disease, which has been very difficult to control, oak wilt can be more readily controlled and this valuable resource saved. Oak wilt, present in many of the eastern states, is most common in the Upper Midwest, including Minnesota. It has spread very slowly north to approximately North Branch and St. Cloud and west to Mankato. The greatest concentrations are in and adjacent to the seven-county metropolitan area surrounding Minneapolis and St. Paul (Figure 1).
SYMPTOMS Red oaks, such as Northern Red Oak and Northern Pin Oak, are highly susceptible to infection by the oak wilt fungus (Figure 2). Oak wilt is easily identified in red oaks by the rapid wilting of affected trees. After symptoms first appear, a red oak will generally wilt completely in two to six weeks. The trees wilt from the top of the crown down and individual leaves wilt from leaf tip and margins to the bases, turning bronze to brown (Figure 3). Fallen leaves are often green at the base. White oaks range in susceptibility from moderate (Bur Oak) to low (White Oak) (Figure 2). Infected white oaks die slowly, a branch at a time, often surviving for many years. Leaf discoloration of affected white oaks resembles autumn colors.
Figure 2. The four most common species of oaks in Minnesota.
In both red and white oaks, the outer ring of springwood vessels will be plugged with brown material (tyloses and gums) and streaks of brown may be obvious on the outside of the wood. The vascular discoloration is most easily seen in cross sections of infected branches of white oaks (Figure 3), and less readily observed in affected red oak branches.
Figure 3. Left: Read Oak leaves in process of wilting. Right: Cross-section of White Oak branches show discoloration often seen as small dark dots in the wood just under the bark.
INFECTION PROCESS The oak wilt fungus spreads in two ways. Most new infections are the result of the fungus moving from infected to healthy oaks via grafted root systems, which are common. Trees as much as 50 feet apart may be grafted together. Root grafts may occur occasionally between different species of oaks. The only way that the fungus can cross highways, rivers, and open fields is by insect vectors, primarily by sap beetles of the Family Nitidulidae. This spread occurs infrequently, but is important as the means by which new oak wilt infection centers are started. Sap beetles are commonly attracted to the sporulating mats produced by the fungus between the bark and wood of oak wilt-killed trees. These mats are commonly produced between April and late June on red oaks that wilted during the previous summer (Figure 4). This is also the same period of time that red oaks produce large springwood vessels and are particularly susceptible to infection. Several species of the same sap beetles are also attracted to fresh wounds on healthy oaks during spring (mid-April to late June). Visitation of such wounds by Ceratocystis fagacearum contaminated beetles then results in oak wilt infection. Oak bark beetles, important oak wilt vectors in some parts of the U.S., and
not considered important vectors in Minnesota.
Figure 4. A sporulating mat produced during May by the oak wilt fungus between the bark and wood of a tree that wilted during the previous summer. The dark area in the center of the mat are pressure pads that crack open the bark.
MANAGEMENT STRATEGIES Stopping spread of the fungus through common root systems is most important and can be done by mechanical barriers using a vibratory plow with a 5-foot blade. Barriers in the soil must be positioned outside of trees with the fungus. Often two lines are recommended: a primary line outside of apparently healthy trees and a secondary barrier outside of every obviously infected tree (Figure 5). The fungus can be in a tree for 23 weeks without leaf symptoms appearing. Barrier placement requires experience. If buried utilities are present, the soil sterilant, Vapam, can be used, but it is not nearly as effective as the mechanical barrier. Overland spread by insects can be prevented by following these guidelines on when to prune and when to paint.
High Risk Period. April, May and June: don't wound or prune! If trees are accidentally wounded or is unavoidable, cover the wounds immediately-within minutes-with one of the preferred materials such as water-based paint or shellac. Low Risk Period. July through October. On rare occasions-depending on weather conditions and insect populations-infections may occur. Covering wounds is optional. Safe Period. November through March. This is the preferred time for since the fungal pathogen and insect vectors are inactive. Tree climbing irons should never be used on living oak trees. As further precaution, infected red oaks on which spores may form in spring (Figure 4) should be eliminated by debarking, burning, burying, or wrapping and sealing in 4-6 ml plastic until July 1. Experience is needed to detect these trees before spores are produced. The spores are carried by the sap beetles to wound oaks during May and June.
Logs from wilting, or recently wilted trees should not be moved in any form, including firewood, to areas where oak wilt is not present. Oak wilt mats may form on these logs. Long distance movement of firewood obtained from such logs has accounted for establishment of oak wilt centers in distant areas that previously had been unaffected by the disease. In high value white oaks, systemic injection with propiconazole by qualified arborists may prevent infection of trees adjacent to oak wilt affected ones. Propiconazole treatment of white oaks exhibiting early symptoms of oak wilt (less than 30% of crown affected) can also prevent further disease development for at least 2 years.
Figure 5. Diagram of root graft barriers around infected trees.
ROOT GRAFT BARRIERS
Vibratory Plow with a Five Foot Blade
FOR OAK WILT CONTROL
A PUBLICATION OF THE MINNESOTA DEPARTMENT OF AGRICULTURE
Printed on 100% Recycled Paper
O
ak wilt is responsible for killing more shade trees each year in Minnesota than any other disease
causing organism or fungus. Fortunately, it can be successfully controlled if proper measures are taken. Oak wilt, caused by a fungus (Ceratocystis fagacearum), attacks the vascular or waterconducting system of oaks, located in the outer ring of sapwood just beneath the bark. In an attempt to protect itself from the fungus, the tree produces gums and tyloses which plug the water conducting vessels. Unable to contain the faster fungus, the tree ultimately cuts off its water and nutrient supply between roots and crown. Visible symptoms (wilting and discoloration of leaves) begin at or near the tree’s top or branch ends and progress down and in, accompanied by rapid defoliation. The oak wilt fungus spreads both overland and underground.
DO NOT PRUNE IN MAY OR JUNE Overland, the oak wilt fungus is spread by picnic b e e t l e s (f ami l y N i t i d u li d a e). These small insects can inoculate a healthy tree only in May or June, and then only when fresh wounds are present. Although less than l0 percent of the oaks dying of oak wilt are believed to be infected this way, it is the only way a new pocket of wilt can start. Control for this type of spread is easy -oak trees should NOT be cut, pruned FIGURE 1. Oak roots often fuse (graft), forming a common or injured from April 15 to July 1. root system on wooded sites. The oak wilt fungus can spread from infected to healthy oaks through these root grafts.
Root transmission is responsible for 90 percent or more of the trees becoming infected from oak wilt. Roots of adjacent oaks (of the same species) within 50 feet of each other are often grafted together, forming a common root system (see figure 1). The oak wilt fungus spreads through a diseased tree’s vascular system, down into its own roots, then through the root grafts into adjacent trees, infecting them as well. What can be done when oak wilt is diagnosed? The answer depends on the species of oak. RED OAK GROUP
Northern Red Oak
Northern Pin Oak
WHITE OAK GROUP
Burr Oak
White Oak
FIGURE 2. The four most common species of oak in Minnesota
WHITE OAKS RESISTANT Trees in the white oak group are resistant to oak wilt. If they become diseased, they may take several years to die or possibly even recover. Bur oaks are intermediate in resistance. Diagnosis of oak wilt and control recommendations in white oaks should be made on an individual basis by a shade tree professional experienced in oak wilt control.
RED OAKS SUSCEPTIBLE Trees in the red oak group are highly susceptible to oak wilt and do not recover if infected. Once symptoms appear, the tree will wilt completely within a few weeks. If other red oaks are nearby, steps should be taken immediately to prevent spread into healthy trees. When oak wilt symptoms are first noticed in red oaks, the fungus has already spread throughout the tree and into the roots. In fact, the fungus often has already infected the root system of adjacent trees, although they may still look healthy because visible symptoms are not yet apparent.
EFFECTIVE TRENCHING PROVIDES BARRIER Control involves severing or breaking the root connections between diseased and healthy oaks (root graft barriers). The most effective barriers are those placed between the first ring of apparently healthy trees adjacent to the infected ones, and the next set of healthy trees (called primary barriers - see figure 3). A barrier placed between diseased and the first apparently healthy oaks (called a secondary barrier) may not stop the disease because the oak wilt fungus may already be in the adjacent ring of trees, but symptoms are not yet visible. To be successful, all roots between infected and healthy oaks must be cut. Mechanical barriers involve physically cutting the roots with either a trencher or a vibratory plow. This work is most effective when a blade or trencher at least five feet long is FIGURE 3. Diagram of barrier placement used. between infected and healthy trees A vibratory plow has a shaker attachment that vibrates a 1-inch thick steel blade up and down (see sketch on the front cover). Its action is similar to that of an electric knife. This machine is fast, and creates only a narrow slit in the ground. Since earth is not removed, backfilling is unnecessary. (Both the vibratory plow and the trencher are typically pulled by large, heavy tractors equipped with flotation tires to minimize soil disturbance.) This method is generally the most cost-effective. A trencher has a boom or blade with a cutting chain that spins around, cutting a trench four to six inches wide. Its action is similar to that of a chainsaw. The trenching blade has a tendency to 'ride up' in the soil, and care should be taken to ensure it remains extended to its' maximum depth. Because a trencher removes earth as it cuts, it is significantly slower than a vibratory plow. Persons hiring contractors with trenchers should ask whether the price includes backfilling the trench.
CHEMICAL BARRIER POSSIBLE Another option is a chemical barrier using a soil sterilant known as SMDC or Vapam. One- to two-inch-diameter holes 18 to 24 inches deep are drilled along the barrier line at four-inch intervals, a Vapam solution is poured into the holes, and the holes covered. Vapam kills all roots, including grass and other plants along a strip about 18 inches wide. Commercially, Vapam may be used only by companies licensed with the state for pesticide application. Whichever barrier method is used, underground utility lines must be located in advance. Diseased trees should not be removed until the root graft disruption work is completed, if trees wilted that same year. If Vapam is used, infected trees should be left standing for two weeks after application. Removing a tree before root systems are separated may actually speed up the spread of oak wilt. (Note: Trees which are structurally weak may present a hazard to people and property, and immediate removal may be warranted - if in doubt, check with a professional.)
EFFECTIVENESS VARIES Mechanical barriers are the most effective method of stopping the spread of oak wilt -- with a success rate approaching 85 percent (with a 5-foot blade). The success rate for chemical barriers is about 55 percent, and is recommended only in areas where use of a plow or trencher isn’t feasible (inaccessible to plow, steep slopes, etc.). Correctly locating these root graft barriers is extremely important to their effectiveness. For the greatest success, seek the advice of a shade tree professional experienced in laying out these lines. Other factors which may affect the success of root graft barriers are soil type, tree size and spacing, and the history of disease in the area. (Note: a map of barrier locations can be invaluable if follow-up work is necessary.) At first, costs for oak wilt control may seem excessive. But the alternative costs of doing nothing (loss of value of healthy trees dying from oak wilt, property value decline, tree removal and increased heating and cooling costs) may be far more expensive. Some contractors charge by the job, by the foot or by the hour. All have a minimum charge to cover the cost of equipment, insurance and transportation. Oak wilt control on a neighborhood or community level is strongly recommended; it can significantly decrease costs while increasing the effectiveness of control work. Persons hiring contractors to do oak wilt control work on their property should ask for references, inquire about experience, and be sure the contractor is insured. RED OAKS DIAGNOSED AS HAVING OAK WILT
Do not remove diseased trees right away. This may accelerate the movement of the fungus into surrounding healthy oaks through root grafts.
Are there other healthy red oaks nearby (within 50 feet)?
YES
Control measures may be necessary. Sever common root systems with a vibratory plow, or trencher, or boom (5 ft. blade), or use chemical means to isolate root systems of infected trees.
NO These trees may produce oak wilt spores during the springtime (the only time insect transmission occurs). These trees need to be removed prior to April 15 of the following year and covered with 4+ mil plastic from April 15 to July 1. This wood can be used.
YES
Did the trees die in July or August?
NO
Unless these trees are in danger of falling on people or property, they can be removed when convenient, and the wood used.
Do not trim or wound healthy oak trees during the springtime, from April 15 to July 1. If an oak is injured at this time of year, cover wound immediately with a non-toxic tree wound dressing.
Figure 4. Flowchart - Oak wilt control in red oaks This brochure was originally developed by David Stephenson with technical assistance from D.W. French, professor of plant pathology at the University of Minnesota. Figure 3 used with permission of the University of Minnesota Extension Service. Figure 1 courtesy of Ken Holman. Additional copies of this publication, or fact sheets on: Organizing a Community Oak Wilt Control Program; Oak Wilt Control and Prevention on Construction Sites; and Oak Wilt in Minnesota are available free of charge by writing to the address below. The oak wilt control program in Minnesota is a multi-agency effort involving the Department of Agriculture, Department of Natural Resources, Minnesota Extension Service, University of Minnesota, USDA Forest Service, and counties and communities across the state. MINNESOTA DEPARTMENT OF AGRICULTURE
OAK WILT CONTROL PROGRAM
Plant Protection Division • 625 Robert St. N. • St. Paul, MN 55155-2538 Telephone: (651) 201-6020 . Fax: (651) 201-6108 . Web: www.mda.state.mn.us Rev. 2/99, RJH
CONTROL: DUTCH ELM DISEASE vs. OAK WILT DUTCH ELM DISEASE
OAK WILT
Spread
Over 90% is overland by beetles
Over 90% is through root grafts
Control emphasis
Bark beetle reduction
Root graft disruption
ROOT TRANSMISSION AND CONTROL When symptoms are first visible Control
The fungus is in the general area of the wilt symptoms (when infection is from beetles). 1. Immediate removal to prevent movement of fungus into roots. Radical if wilt is very isolated.
The fungus is throughout the tree and into the root system. Root graft disruption if healthy oaks (of the same species) are nearby. Do not remove the tree first!
2. If the infection is from root transmission, root graft disruption should be done first!
AERIAL TRANSMISSION AND CONTROL Beetle characteristics 1. Attracted specifically to elms 2. Can chew through bark
1. Not attracted specifically to oaks 2. Can only enter a tree through fresh wounds
3. Can travel long distances 3. Does not travel very far 4. Active all summer 4. Active primarily in springtime 5. Breeds in dead or dying bark-intact elm wood
Control
5. Does not breed in oak wood 1. Don’t prune in April, May and June!
Remove and dispose of all dead/dying bark-intact elm wood. This will remove the breeding sites of the beetle.
2. Locate, remove and dispose of diseased oaks producing spores in early spring (March and April).
Plant Protection Division 625 Robert St. N. St. Paul, MN 55155-2538 651-201-6020 Rev. 2/99, RJH
OAK WILT CONTROL TIMETABLE JAN
FEB
MAR
APR
MAY
JUNE
JULY
Cover hazardous wood *Oak removal & proper disposal: mid-Nov to March 31st
Disease
JAN
FEB
MAR
AUG
SEPT
OCT
MAY
DEC
Root graft disruption (until ground freezes) *Oak removal & proper disposal: mid-Nov to March 31st
Field ID of diseased oaks
APR
NOV
JUNE
JULY
AUG
SEPT
OCT
NOV
DEC
transmission
through wounding
SAFE period
HIGH risk period
LOW risk period
SAFE period
*NOTE: Spore mats in infected trees can be observed throughout the winter. In order to prevent overland spread, infected trees (shown to produce spore mats) need to be properly wrapped/disposed of by March 31st.
DUTCH ELM DISEASE CONTROL TIMETABLE JAN
FEB
MAR
APR
MAY
JUNE
JULY
AUG
SEPT
OCT
NOV
DEC
High-risk elm ID Elm firewood ID & disposal (Disposal of lowrisk elms from previous year by 4/1)
Low-risk elm ID
1st Insp.
2nd Insp.
3rd Insp. Inspection of healthy elms Root graft disruption (until ground freezes)
NOTE: High-risk elms must be removed within approximately twenty days. Low-risk should be removed within twenty days, but no later than April 1 of the following yea
University of Minnesota- Forest Resources Extension & Outreach, 2007. Adapted from Minnesota Department of Agriculture, RJH 1999 version. Oak wilt reviewer, Jennifer Juzwik, USDA Forest Service- Research Plant Pathologist
1. Oak wilt is caused by: A. a bacteria. B. sap beetles. C. a virus. D. a fungus.
2. The primary emphasis of oak wilt control is: A. prompt removal. B. reforestation. C. root graft disruption. D. elimination of beetle breeding sites.
3. The “safe period” for oaks in Minnesota is July through the following April. A. True B. False
4. Wounding of oak trees should be avoided during April, May and June because: A. sap beetles, which carry the spores, are attracted to these fresh wounds. B. wind-blown spores could land on these fresh wounds. C. freshly wounded oaks can only be infected with oak wilt at this time of year. D. A and C. 5. Which of the following oak species die more rapidly from oak wilt? A. Red oak. B. Northern pin oak. C. White oak (including bur). D. A and B. 6. The most effective method of root graft disruption is: A. vibratory plowing or trenching with 60" blade or boom. B. soil sterilizing treatment C. immediate removal of the diseased tree and stump. D. removing the healthy oaks closest to the diseased tree.
*Answers for all “Section Quizzes” are located at the end of this manual.
Extension Bulletin E-2938
Reprinted December 2005
Signs and Symptoms of the Emerald Ash Borer Mary Wilson, MSU Extension. Eric Rebek, Michigan State University Dept. of Entomology
Adult A
Larva
B
C
D. Cappaert, MSU Michigan State University
Michigan State University
• Bright, metallic green (Figs. A, B). • 1/2 inch long, flattened back (Figs. A, B). • Purple abdominal segments beneath wing covers.
• Creamy white, legless (Fig. C). • Flattened, bell-shaped body segments (Fig. C). • Terminal segment bears a pair of small appendages.
Canopy Dieback E
D
Epicormic Shoots F
• Sprouts grow from roots and trunk (Figs. F, G).
J. Smith, USDA APHIS PPQ
G E. Rebek, MSU
E. Rebek, MSU
• Begins in top one-third of canopy (Fig. D). • Progresses until tree is bare (Fig. E).
MICHIGAN STATE U N I V E R S I T Emerald Ash Borer
Y
EXTENSION
J. Smith, USDA APHIS PPQ
• Leaves often larger than normal.
Signs and Symptoms o f Emerald Ash Borer
Serpentine Galleries and D-shaped Exit Holes
Bark Splitting H
J
I
J. Smith, USDA APHIS PPQ
A. Storer, Mich. Tech. Univ.
K
D. Cappaert, MSU
• Vertical fissures on bark (Fig. H) due to callous tissue formation (Fig. I).
D. Cappaert, MSU
• Larval feeding galleries typically serpentine (Fig. J). • Galleries weave back and forth across the wood grain. • Packed with frass (mix of sawdust and excrement). • Adults form D-shaped holes upon emergence (Fig. K).
• Galleries exposed under bark split.
Increased Woodpecker Activity/Damage L
M
D. Cappaert, MSU
Karen D’Angelo, MSUE
• Several woodpecker species (Fig. L) feed on EAB larvae/pupae. • Peck outer bark while foraging (Fig. M). • Create large holes when extracting insects (Fig. M).
MICHIGAN STATE U N I V E R S I T Y
EXTENSION
MSU is an affirmative-action, equal-opportunity institution. Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, marital status, or family status. • Issued in furtherance of Extension work in agriculture and home economics, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Thomas G. Coon, Extension director, Michigan State University, E. Lansing, MI 48824. • This information is for educational purposes only. References to commercial products or trade names do not imply endorsement by MSU Extension or bias against those not mentioned. This bulletin becomes public property upon publication and may be printed verbatim with credit to MSU. Reprinting cannot be used to endorse or advertise a commercial product or company. Revised - 12:05 - 5M - KMF/LB
Emerald ash borer in Minnesota Jeffrey Hahn, Extension entomologist 2013
On this page
Why is this insect important?
How do I recognize this insect?
Symptoms and damage
Biology
What can I do to help?
What can I do if I suspect I have found EAB?
Should I be planting or removing ash?
Should I treat my ash?
Credit: Jeff Hahn
An EAB adult
Credit: Jeff Hahn
An EAB adult with wings open The emerald ash borer (EAB), Agrilus planipennis, is a very destructive insect pest of ash trees (Fraxinus spp.), the only known hosts of this borer in North America. This exotic borer is a native of Asia with its natural range including China, Japan, Mongolia, Korea, the Russian Far East and Taiwan. It was first discovered in North America in southeast Michigan in June, 2002, although it was likely introduced as much as 10 years earlier. It was first found in Minnesota in May 2009, in St. Paul.
Why is this insect important? This destructive beetle has killed tens of millions of ash trees where it has been discovered. There are nearly one billion ash trees in Minnesota, the largest concentrations of ash of any state in the country. Not only are these trees abundant in our forests, but they are also an important component of our urban landscapes. Research has not found any resistance in our native ash. We could lose much of this resource.
Click image to expand
Insects in Minnesota that may be confused with EAB. Click here for a PDF of this image (457 K PDF).
Credit: Pennsylvania Department of Conservation and Natural Resources – Forestry Archive
An EAB larva
How do I recognize this insect? EAB is a slender, elongate insect about 1/3 to 1/2 inch long. It is widest just behind the head, gradually tapering back to the abdomen. It is a bright iridescent green to copper-green color, often with a copper colored area behind the head. Its body underneath the wings is a purplish-magenta color. This borer is a type of metallic wood boring beetle (family Buprestidae) and is closely related to the bronze birch borer and the twolined chestnut borer, both native insects in Minnesota. EAB, however, is a little larger and much more brightly colored than these species. Not every green insect you see is an EAB. There are several common insects that look similar, especially the sixspotted tiger beetle and the polydrusus weevil. A six-spotted tiger beetle is a similar size, about 3/8 to 1/2 inch long but with a conspicuous, large head and eyes. It is also a different shape with the abdomen being wider than the head. The polydrusus weevil is a small, 1/4 inch long, oval insect with a short snout. It has a black body covered with pale metallic green scales. Also, not every insect you find attacking ash is an EAB as there are many native ash borers present in Minnesota. The most common are redheaded ash borer, bark beetles and clearwing borers. For more information see native borers and emerald ash borer look-alikes (4.96 MB PDF).
The larvae have flat, slender, whitish colored bodies. They are 1 to 1 1/4 inches when fully grown. These larvae have a small brownish head that is just visible. They lack legs but do possess a pair of small pincher-like appendages on the tip of their abdomen.
Symptoms and damage (Links can be explored on electronic manual only) Select any image to open a slideshow.
Woodpecker activity.
Vertical splitting of the bark.
Thinning canopy can be caused by many other factor, not just E.A.B.
D-shaped exit holes are a “telltale” sign but are often difficult to locate.
S-shaped galleries under the bark distinguish E.A.B. from most native borers.
Ash can tolerate small numbers of EAB larvae but trees are girdled and killed as the pest quickly increases in numbers. Trees are often killed in about four years, although it can take as little as two years. When trees are first attacked by EABs, the symptoms are inconspicuous and hard to notice. During the second year, woodpecker pecks and thinning foliage begin to be apparent. By the third year, woodpecker activity is more common and canopy thinning is more pronounced. Vertical bark cracks (due to the tree trying to heal over old galleries) may also be present. Although woodpecker activity and vertical bark splits are not always caused by EAB, they are common symptoms in EAB infested ash trees. By the fourth year, the canopy has seriously declined and may even be dead.
When the adults emerge, the small, 1/8 inch D-shaped exit holes they create are characteristic of this insect, although they can be hard to see. If you were to remove the bark on the trunk of a tree showing these symptoms, the Sshaped galleries formed by the larvae are also diagnostic of EAB activity. Epicormic sprouts may form on the lower trunk and major branches as the tree responds to emerald ash borer tunneling although this typically occurs when trees are almost dead and does not automatically indicate EAB. All North American ash species are attacked, including all ash species found in Minnesota: green (F. pennsylvanica), black (F. nigra), and white ash (F. americana). Mountain-ash (Sorbus. spp.) are not true ash and are not attacked. Emerald ash borer attacks ash of different sizes from as small as one inch diameter to large mature trees. They prefer stressed and unhealthy trees, similar to the native bronze birch borer and twolined chestnut borer. However, unlike these insects, EABs will also successfully attack vigorously growing trees. Once an ash is attacked by EABs, it will be killed if it is not protected. Keep in mind there are other problems that can cause an ash tree to decline. Go to What's Wrong With My Ash? for help in diagnosing an ash problem.
Biology EABs generally have a one year life cycle although that can be extended to two years in a vigorously growing host. These insects overwinter as fully grown larvae in chambers constructed under the bark of ash trees. They pupate in early spring and emerge as adults, leaving characteristic D-shaped emergence holes. Depending on where you live in Minnesota, expect adults to emerge any time from late May to August. After feeding on leaves, adults mate and females lay eggs on the bark or into small cracks. Eggs hatch in 7 to 10 days. The whitish larvae, called flatheaded borers, tunnel under the bark creating winding, S-shaped galleries in the phloem and outer sapwood. These tunnels girdle the trunk and branches, interrupting the flow of water and nutrients. The larvae feed until fall and then overwinter as prepupal larvae.
What can I do to help? First, don't transport firewood when you go camping or are buying it for home use. Buy the wood you need at local sites or at the campgrounds you are visiting. On its own, most EAB will generally move only about 1/2 to 1 mile a year from infested sites. But with help from people, it can travel hundreds of miles when carried in firewood and other wood products or nursery stock. Next, be aware of what an EAB looks like as well as the symptoms of an EAB infested tree. Report any suspect insects or declining ash trees (see the following section "What can I do if I suspect I have found EAB?"). There have been many cases where the public was the first to find an initial infestation in an area.
What can I do if I suspect I have found EAB? First, use the diagnostic page (2,248 K PDF) to see if you can clearly rule out EAB. If, after you have gone through this page, you can't easily rule out EAB, then contact the Minnesota Department of Agriculture (MDA) on their Arrest the Pest phone line at 1-888-545-6684 to report your suspicions.
Should I be planting or removing ash? Because of the overabundance of ash in urban landscapes and other sites, it is strongly recommended not to plant additional ash. Consider the other woody plant options that are available to Minnesotans. The more diverse the plantings of trees in the urban landscape are, the better neighborhoods can tolerate future pest problems.
However, if you have an ash in your yard and it is healthy, there is no reason to remove it. As long as it is a low maintenance plant, keep it in your landscape.
Should I treat my ash? There are several factors to consider when deciding whether to treat your ash. First, if your ash tree(s) is within 15 miles of a known infestation, it is at a higher risk of being attacked by EAB. Currently, EAB has been confirmed in four counties in Minnesota: Ramsey, Hennepin, Houston, and Winona. If your tree(s) is beyond 15 miles from any known infestation, it is not advised to treat it until at least EAB is confirmed in your area. The further your ash is from a known occurrence of EAB, the less likely that it will become infested. Also consider the health of your ash. The tree is a good candidate to protect if it still has most or all of its canopy. However, if it has lost half of its canopy or more, it is in poor health and treatment is very unlikely to be effective. Also consider the tree's importance to you. If it is a valued tree, then considering protecting it. Healthy, mature trees improve the attractiveness of a landscape, raise property values, help reduce energy costs, and decrease storm water runoff. See also Managing Emerald Ash Borer: Decision Guide (764 K PDF) The insecticides available for treating EAB have been shown to be effective in protecting ash in University research trials. Some products are available to residents so they can treat ash themselves. However, larger ash trees (> 15 inches d.b.h., i.e. at 4 1/2 feet above the ground) are generally best treated by a professional arborist. Trees do not build up any resistance because of the insecticide applications and need to be treated on a regular basis (every one to two years depending on the insecticide that is used). For specific information on insecticides available for treating EAB, see Emerald Ash Borer: Homeowner guide to Insecticide Selection, Use, and Environmental Protection (788 K PDF). If you decide that you would rather not treat and protect your ash, consider removing the tree. Keep in mind that the larger the tree is, the more expensive it is to remove. Also, it is easier (and less expensive) to remove the tree while it is alive. Once an ash tree is dead, the branches become brittle making it much more challenging to cut down. Any time you consider hiring a professional arborist to care for your trees, be sure to ask for certificates of insurance and local references. Get at least two estimates and don't rush into a decision because you are promised a discount. For more information, see How to hire a professional arborist to help care for your landscape trees. For more information on EAB, see the Extension emerald ash borer page.
1.
Emerald ash borer is spread long distances primarily by: A. transporting infested firewood. B. the adult beetle flying up to 50 miles per year. C. infested tools. D. climbing spikes/gaffs.
2. Signs and symptoms of emerald ash borer infestation include: A. D-shaped exit holes. B. epicormic sprouts. C. crown decline. D. all of the above.
3. Emerald ash borers are only present in the outer one inch of the bark/wood so once that is removed; the remaining wood is useable or non-infested. A. True B. False 4.
5.
6.
Which of the following tree species is not attacked by emerald ash borer? A. Green ash B. Blue ash C. Mountain ash D. White ash
How does the emerald ash borer kill trees? A. Defoliation B. Sap-sucking C. Feeds on shoots and twigs D. Feeds in sapwood
Once an ash tree becomes infested with emerald ash borer: A. It usually dies within one year. B. There are chemical treatments that can prevent death if the tree doesn’t have too much dieback. C. The tree will likely survive if it is fertilized each year and watered regularly. D. The adult insect can be killed with a foliar insecticide, thus preventing further damage.
*Answers for all “Section Quizzes” are located at the end of this manual.
United States Department of Agriculture Forest Service Northeastern Area State and Private Forestry NA–PR–02–11 May 2011
Bur Oak Blight A serious leaf blight disease on bur oak has been recognized in several Midwestern States since the 1990s with Iowa reporting its first occurrence of this disease 6 or 7 years ago. A common leafspot fungus, Tubakia dryina, was initially thought to be the cause of the blight on bur oak, but closer examination revealed a different story. Researchers in Iowa confirmed that this disease is caused by a new, and yet unnamed, species of Tubakia. The disease was named bur oak blight, or BOB for short. There are now five known species of Tubakia that can infect bur oak in Iowa, but only one species causes dramatic leaf symptoms and tree mortality characteristic of BOB.
Hosts and Distribution BOB occurs only on bur oaks. Severe symptoms of BOB have been observed only on Quercus macrocarpa var. oliviformis, a variety of bur oak that produces smaller acorns. BOB occurs primarily on naturally established trees, and especially on mature trees on upland sites that appear to be remnants of savannah forests. Bur oak growing in dense forests and on bottomland sites is less seriously affected. It is not clear if this new species of Tubakia is a recent arrival to this region or if a shift in climate (more early-season rain events) has made this disease more noticeable over the last two decades. To date, the BOB fungus is known to occur from northeastern Kansas and eastern Nebraska to central Minnesota and southwestern Wisconsin, and across most of Iowa. This disease is most severe in eastern Nebraska, Iowa, and Minnesota, which coincides closely with the distribution of Quercus macrocarpa var. oliviformis. A few affected trees have also been identified in Illinois and Missouri.
10X magnifying lens (figure 4). Later in the season, black pustules (fruiting bodies of the fungus) develop on the petioles of infected leaves (figure 5), and mature spores are seen in these pustules the next spring. A unique feature of BOB is that some of the killed leaves Figure 1.—Purple-brown lesions develop remain on the tree along the veins on the underside of leaves. during the winter (healthy bur oak trees shed all of their leaves in the fall). Not all infected leaves, however, remain attached. Some leaves drop off during the growing season and some are blown off by winter winds (figure 6). If BOB-infected leaves drop or are blown off, their petioles typically remain attached to the tree. The disease can be confirmed by microscopic examination of the pustules that form on the petiole base. The disease tends to intensify from year to year in individual trees. If only a portion of the crown is affected, BOB symptoms usually start in the lower branches and progress up the tree. If a tree is seriously affected one year, it tends to be severely affected the next year. BOB appears to spread slowly, particularly from tree to tree. It remains a mystery why BOB does not spread more rapidly given the great abundance of spores that cause BOB and their spread by rain.
Symptoms Leaf symptoms typically first appear in late July or August. Infected leaves develop purple-brown lesions along the midvein and major lateral veins on the underside of leaves (figure 1). As the lesions increase in size, dark veins become noticeable on the upper leaf surface (figure 2). Large, wedgeshaped areas of chlorosis and necrosis develop on the leaf blade, and major leaf mortality may occur (figure 2). Individual lesions may coalesce and cause large areas of the leaf to die, giving it an overall wilted or scorched appearance (figure 3). The symptoms of wilting and leaf scorch resemble, and have been confused with, symptoms induced by oak wilt. During the summer, black fruiting structures of the fungus form along the dark leaf veins and produce rain-splashed spores. These fruiting bodies can be seen with the aid of a
Figure 2.—Dark veins and large wedge-shaped lesions develop.
Not all stands of bur oak are seriously affected by this disease. Even within a seriously affected stand, not all trees are equally susceptible. Some trees may be severely infected while adjacent trees appear healthy (figure 7). This is likely due to variation in the resistance of individual bur oak trees to this disease.
Management
Figure 3.—Large areas of the leaf may die, resulting in an overall wilted or scorched appearance.
Over time, severely affected trees may die. Tree death is usually associated with severe blight over many years and damage caused by secondary invaders such as the two-lined chestnut borer and Armillaria root rot. Boosting tree vigor may prolong the life of affected trees and ward off invasion by secondary pests. Because the fungus overwinters on infected leaf petioles that remain on the tree, removing fallen leaves is not an effective management tool. In preliminary studies, injections of the fungicide propiconazole (Alamo formulation) in late May or early June (prior to leaf symptoms) have reduced symptom development in the fall and the following year. With further study, fungicide treatments may have value in managing high-value landscape trees.
Sample Submission When collecting samples for BOB testing, collect branch twigs with symptomatic and healthy leaves as well as petioles from several locations on the tree and wrap them in dry paper toweling (no plastic bags, please). Figure 4.—Black fruiting bodies form on dark leaf veins (lower right). Rain-splashed spores are produced under a protective hyphal shield (upper right, magnified 200X).
Figure 5.—Black pustules develop on infected leaf petioles.
Submit samples to the National Plant Diagnostic Network (NPDN) Clinic in your respective State. To find a clinic near you, go to http://www.npdn.org/.
Contact information for authors: Jill D. Pokorny, Plant Pathologist, U.S. Forest Service, Northeastern Area State and Private Forestry, Forest Health Protection, 1992 Folwell Ave., Saint Paul, MN 55108 651–649–5247 Dr. Thomas C. Harrington, Iowa State University, Department of Plant Pathology, 221 Bessey Hall, Ames, IA 50011 Photo credits: Figure 6.— Many dead leaves remain on the tree throughout the winter.
Figure 7.— Affected trees typically occur next to unaffected trees.
The USDA is an equal opportunit y provider and employer. Federal Recycling Program Printed on recycled paper.
Dr. Thomas C. Harrington, Iowa State University Jill D. Pokorny and Joseph G. O ’Brien, U.S. Forest Service
Published by: USDA Forest Service Northeastern Area State and Private Forestry 11 Campus Boulevard Newtown Square, PA 19073 www.na.fs.fed.us
American and Oriental Bittersweet Identification
I
nvasive species are one of the greatest threats to native ecosystems. They can crowd out native species and change the natural nutrient cycling processes that take place in ecosystems.
One of the best ways to combat invasive species is by identifying small infestations and removing them. One invader threatening midwestern ecosystems is oriental bittersweet (Celastrus orbiculatus). This woody vine was introduced to the eastern United States in the mid-1800s. It has spread from the east to the south and west and is now moving into midwestern natural areas. Oriental bittersweet can be found in a variety of habitats, from roadsides to interior forests and sand dunes. It has the ability to girdle and overtop adjacent vegetation – often to the detriment of native species. To halt the spread of oriental bittersweet, significant control measures are needed. However, a native bittersweet species, American bittersweet (Celastrus scandens), can be mistaken for oriental bittersweet. Although American bittersweet is also a
American bittersweet vine and climbs on nearby vegetation, it does not appear to grow as rapidly or as large as oriental bittersweet. In the northeastern United States, American bittersweet is declining because of habitat change and possible hybridization, while in the Midwest, it is still common. Because the two bittersweet species look so similar, there can be difficulty knowing U.S. Department of the Interior U.S. Geological Survey
which plants to target for control. Using fruit and leaf characters, the two species can be discriminated from each other. However, certain traits are more reliable for correct identification than others. Classically, the position of the fruit and flowers on the stems has been cited as the most definitive means of discriminating between the species. Oriental bittersweet has fruit and flowers located in the leaf axils along the length of the stem. American bittersweet, however, only has fruit and flowers in terminal clusters. There is also a difference in the color of the capsules surrounding the ripened fruit in the fall. Oriental bittersweet has yellow capsules, while those of American bittersweet are orange. Another difference in color is the pollen color of the male flowers. The pollen of oriental bittersweet is white while that of American bittersweet is yellow. Some less definitive fruit traits for discrimination are size of the fruits and number of seeds per fruit. American bittersweet has generally larger fruit than oriental bittersweet. If fruits have a volume of greater than 250 mm3, there is a 90% probability of a plant being American bittersweet, while if the fruit has a volume of 115 mm3 or less; it has a 90% chance of being oriental bittersweet. Values in between these numbers overlap to some extent between the species. Similarly, if the fruit has one or fewer seeds, it is 90% likely to be American bittersweet, while five or more seeds have a 90% chance of being oriental bittersweet. The greater number of seeds of oriental bittersweet gives it a reproductive advantage over the native species. The problem with using fruit and flower traits for discriminating between the two species is that, for fruits, only mature Great Lakes Science Center 1451 Green Road Ann Arbor, MI 48105 (734) 994-3331 www.glsc.usgs.gov
Oriental bittersweet female plants have this character available for identification. In terms of flowers, only mature male and female plants have these present, and only for a brief time of the year during the spring. Vegetative traits apply to plants regardless of their sex or maturity. The most definitive vegetative trait is the posture of the leaves at leaf out of the first buds in the spring. The leaves of oriental bittersweet are conduplicate (two sides of the leaf folded against each other) and tightly packed in the bud when they emerge in the spring. The leaves of American bittersweet are involute (leaf margins rolled in like a scroll) and not as tightly packed in the bud. Other leaf traits are not as reliable as the leaf-out posture. Although the ratio of length-to-width (length:width) of the leaves is generally greater for American bittersweet, this trait is quite variable. If the length:width of the leaf is greater than or equal to 2, there is a 90% chance of the plant being American bittersweet, while if the ratio is less than or equal to 1.4, there is a 90% chance of it being oriental bittersweet. The tips of the leaves of American bittersweet are also generally longer than those of oriental bittersweet. Plants with leaf tips of 1.5 cm or greater have a 90% chance of being American bittersweet, while plants with leaf tips of 0.3 cm or less have a 90% chance of being oriental bittersweet. By using these traits, plants could be marked at the appropriate time of year (spring or fall) for control at a later point. In this manner the invasive species can be targeted without harming the native. The key on the next page summarizes the key traits for discrimination of these two species in the field.
GLSC Fact Sheet 2007-2
Is plant in fruit?
Are ripe fruit capsules orange?
Yes
C. scandens
yellow?
No
C. orbiculatus
Are fruit borne in terminal panicles?
axillary cymes?
C. scandens Do fruits have ≤ one seed?*
C. orbiculatus C. scandens
≥ five seeds?* Is plant in bloom?
Yes
C. orbiculatus
Are flowers borne in terminal panicles?
No
C. scandens
axillary cymes? Are flowers staminate?
Yes
Is pollen
yellow?
white?
C. scandens Is plant leafing out? Yes
C. orbiculatus Are leaves
No
involute?
C. scandens Are mature leaves present?
C. orbiculatus
Yes
No
conduplicate?
C. orbiculatus
Is length:width ≥ 2.0?*
C. scandens
Is length:width ≤ 1.4?*
C. orbiculatus
Is leaf tip > 1.5 cm?*
C. scandens
Is leaf tip < 0.3 cm?*
C. orbiculatus
If dormant season, only fruit characters applicable * Indicates a 90% probability of correct identification based on the data collected for this study. Colors in text boxes are to be used as a guide only, actual colors seen in the field may differ.
Collaborators: Noel B. Pavlovic, Stacey Leicht Young, Ralph Grundel, and Krystalynn J. Frohnapple
United States Department of Agriculture Forest Service Northeastern Area State and Private Forestry NA–PR–04–0
Forest Tent Caterpillar The forest tent caterpillar (Malacosoma disstria Hübner) is a native insect found throughout the range of hardwood forests in North America. It is more abundantly distributed in eastern North America, but is also common in western areas that have large stands of aspen. At times, this insect can be a damaging defoliator of trees. Trees that are defoliated often flush a new, smaller set of leaves in July. While forest tent caterpillar does not typically cause mortality to host trees, mortality can occur when populations interact with other disturbances, such as drought or insect outbreaks. Forest tent caterpillar larvae use silk to form trails and to create pads on host trees where they congregate and rest. However, they do not construct and reside within elaborate silken tents. A different species, the eastern tent caterpillar, forms these more defined tents in branch crotches of cherry and other trees in the rose family.
Figure 1. Forest tent caterpillar egg masses
Figure 2. Forest tent caterpillar larvae
Hosts Because forest tent caterpillar is found throughout much of North America, it is no surprise that it has a large host range. Depending on the geographic region, ash, aspens, basswood, birch, cherry, cottonwood, elms, oaks, red alder, sugar maple, swamp blackgum, sweetgun, water tupelo, and willow are all potential hosts. Forest tent caterpillar does not feed on red maple, sycamore, or conifers.
Figure 3. Forest tent caterpillar pupa in cocoon
Description Eggs are laid in dark masses (25–37 mm wide) that surround small twigs (figure 1). These masses may contain up to 350 eggs. Newly hatched larvae are 3 mm in length, black, and have noticeable hairs. As larvae grow and become a more brownish color, two distinct characteristics develop. Pale bluish lines form along the margins of the larvae, and white spots (often described as footprints or keyholes) develop along the back (figure 2). Full-grown larvae are about 50 mm in length. Pupae are protected by a cocoon spun from pale yellow silk and are often found in protected areas (figure 3). Adult moths are light brown with two narrow dark bands on the forewings and have a wingspan between 25 and 28 mm (figure 4)
Figure 4. Forest tent caterpillar adult moth
Life History Forest tent caterpillar populations usually cycle, remaining high for 3 to 4 years before dropping to low levels due to harsh weather, predation, disease, and/or starvation. Eggs hatch in the spring and larvae begin feeding on the newly expanded foliage of host trees. During this time, larvae can be seen following one another in straight lines and congregating. Larvae feed into June and
then pupate in silken cocoons in protected areas or folded leaves. Adults emerge in July, locate hosts, mate, and lay eggs. Egg masses are deposited around small twigs of host trees and are often concentrated on trees near well-lit urban areas. The adult moths are nocturnal and are strongly attracted to light. Management Options Several options are available for managing forest tent caterpillar. Because trees usually survive defoliation, the first option to consider is doing nothing to manage the population. Environmental conditions as well as natural predators help regulate forest tent caterpillar populations after only a few years. If control is necessary, mechanical and insecticidal options exist. Mechanical options include placing barriers on trees, removing egg masses before they hatch, and removing larvae when they are congregated. Insecticides such as Bacillus thuringiensis (B.t.) can be used to protect weakened trees or to cover large areas where populations have remained high for consecutive years. Management decisions can be guided by egg mass surveys. For example, an average of 20 or more egg masses over 15 cm in diameter per tree indicates the likelihood of complete defoliation and may necessitate a management response.
Pesticide Precautionary Statement Pesticides used improperly can be injurious to humans, animals, and plants. Follow the directions and heed all precautions on the labels. Note: Some States have restrictions on the use of certain pesticides. Check your State and local regulations. Also, because registrations of pesticides are under constant review by the Federal Environmental Protection Agency, consult your county agricultural agent or State extension specialist to be sure the intended use is still registered. Authors: Kevin J. Dodds, USDA Forest Service, Northeastern Area State and Private Forestry, Forest Health Protection, Durham, NH Steven J. Seybold, USDA Forest Service, Pacific Southwest Research Station, Davis, CA Photo credits: Ronald S. Kelley, Forest Insect and Disease Specialist, Vermont Department of Forests, Parks and Recreation, Morrisville, VT For more information, contact the office nearest you: USDA Forest Service Forest Health Protection 271 Mast Road Durham, NH 03824 603.868.7600
USDA Forest Service Northeastern Area State and Private Forestry Newtown Square, PA
USDA Forest Service Forest Health Protection 1992 Folwell Avenue St. Paul, MN 55108 651.649.5243
USDA Forest Service Forest Health Protection 180 Canfield Street Morgantown, WV 26505 304.285.1542
The USDA is an equal opportunity provider and employer.
USDA Forest Service Forest Health Protection 1720 Peachtree Road NW, Rm. 862N Atlanta, GA 30367 404.347.2961
http://www.na.fs.fed.us
1. A homeowner notices a loss of foliage and “well defined” leaf scorch in their mature oak tree. They show you a healthy leaf matching the shape of example illustrated below. What statement(s) can be safely determined? A. B. C. D.
This tree may have oak wilt. This tree may have bur oak blight. This tree most likely has oak wilt. Nothing can be determined using only a leaf.
2. Which statement below is FALSE? A. B. C. D.
Bur oak blight occurs primarily on naturally established, mature oaks. Winter “leaf-cling” is a unique symptom to bur oak blight. Even a healthy bur oak will retain some of its leaves through a mild Minnesota winter. In severe cases of B.O.B., death is usually caused by secondary “invaders” such as Armarilla root rot or two-lined chestnut borer. 3. Choose the best answer. Forest tent caterpillars will NOT feed on the following: A. B. C. D. E.
Sugar maples, oaks or ash species. Birch, alder or conifers. Red maple, sycamore or conifers. Cottonwood, sugar maples or willow. It’s a trick question, forest tent caterpillars will feed on all trees and shrubs.
4. True or False: In regards to forest tent caterpillars, tree’s will usually survive defoliation and, predators and environmental conditions usually help to regulate the population after only a few years. Doing nothing as far as management should be the first consideration. A. True B. False 5. Some traits that differentiate oriental bittersweet from native (American) bittersweet are: A. Oriental bittersweet has fruit and flowers located in the leaf axis along the length of the stem. American bittersweet, however, only has fruit and flowers in terminal clusters. B. In fall, the capsules that surround the ripened fruit of the oriental bittersweet are orange, in American bittersweet they are yellow. C. In fall, the capsules that surround the ripened fruit of the oriental bittersweet are yellow, in American bittersweet they are orange. D. Both A and B are correct. E. Both A and C are correct. 6. True or False? You can determine with about 90% accuracy, the difference between American bittersweet and oriental bittersweet by simply counting the seeds in the ripened fruit. A. True B. False
*Answers for all “Section Quizzes” are located at the end of this manual.
BEST PLANTING PRACTICES The information presented in this section represents the most current and well researched information being utilized by foresters and tree care professionals statewide. Topics range from planting, species selection, loading events and an overview of the gravel bed culture. “Best Practices” as defined for this manual means letting holistic, pragmatic and biologically sound information guide your community tree decisions. These videos were developed by The University of Minnesota, Forest Resources, Urban and Community Forestry Team. They illustrate topics including: correction of less viable nursery stock, correct planting of multiple stock types, tree staking options and stem protection. Video’s are under 5 minutes each and contain materials that will be on the Minnesota Tree Inspector Exam. TOPIC
LINK
Planting Balled and Burlapped Nursery Stock
http://youtu.be/BCzEaJ5OqtE
Planting Standard Nursery Potted Stock
http://youtu.be/R3I5qujp9Gw
Planting Less Typical Stock Types
INFORMATION INCLUDING: • • • • •
Safely moving stock. Adjusting planting depth. Hole “architecture”. Basket removal. Planting.
• • • • •
Pre-purchase inspection. Adjusting for planting depth. Removal of encircling or girdling roots. Sprout . Planting.
• • •
Adjusing planting depth. Removal of stock from container. Planting.
• •
Material recommendations. Single and multiple staking techniques.
•
Different protection types for different needs. Materials. Installation.
*Not on 2014 Exam Unavailable Staking *Not on 2014 Exam
Unavailable *Not on 2014 Exam
• • Unavalable
Three Steps for Planting Trees & Shrubs University of Minnesota, Department of Forest Resources â&#x20AC;&#x201C; December 10, 2013 A tree that lives to 125 years in the forest will on average live less than 10 years in downtown sites and 35 years in the suburbs (Moll, 1989). Poor planting practices can shorten a treeâ&#x20AC;&#x2122;s life span. This fact sheet will help guide you through the best planting practices to insure the beauty and health of your trees and shrubs. Step 1: Bringing your trees and shrubs home Keeping roots moist is important during the move as moist roots help the tree establish quickly. Wrap the soil ball, container, or bare roots in a tarp or large garbage bag to trap moisture until planting time. Step 2: Planting your trees and shrubs Bare root trees/shrubs: Bare root trees and shrubs come without any soil around the roots. Make sure the planting hole is wide enough to fit all roots inside. Dig the hole deep enough so the first main lateral root is within 1 inch of the soil surface. A common planting error is digging holes too deeply.
Then check to see if there is excess soil on top of the root system (often there is at least 4 inches of excess soil over the first main lateral root). Use a kabob skewer or straightened coat hanger to probe next to the stem into the soil ball until the first main lateral root is felt. If there is more than an inch of soil over those roots, use a saw to cut off the extra soil.
Removing excess soil prevents future stem problems and promotes healthy root systems. Next, check for encircling roots.
Containerized trees/shrubs: Remove the tree or shrub from the container by lifting it up by the stem and tapping down on the rim of the container.
Remove encircling roots by sawing off the Step 3: Caring for your tree/shrub sides of the soil ball. Mulch: Create a mulch in a ring that is 2 to 4 inches deep and 6 feet in diameter around the tree. Keep the mulch off the trunk. This will help hold moisture in the soil and prevent trunk damage from lawn care machinery. Stake (only trees that lean or fall over need to be staked):
This encourages a healthy, spreading root Use two or three stakes to secure a tree. system. Attachments should be two-thirds of the Dig a hole that is at least double the distance from the ground to the first diameter of the soil ball. Doubling the branch and stakes should be driven into diameter of the hole makes it easier to the ground at least 18 inches deep. It is position and water the plant. More water best to use a wide material such as soaks into the loose soil, rather than canvas burlap or an old bicycle inner tube running off the top of the soil surface. to loosely attach the tree trunk to the Measure the distance from the first main stakes. This allows the tree to move lateral root to the bottom of the soil ball to slightly with out damaging the bark. After determine the hole’s depth and ensure one growing season the tree will be that the first main lateral roots are within 1 established and stakes should be inch of the soils surface. removed to allow for correct development. Place the tree in the hole, making sure it Water: stands straight and backfill the hole with Thoroughly water the tree at planting. the original soil. Then water your tree a couple times a Planting balled and burlapped week for a total of 15-25 gallons per week trees/shrubs: until the ground freezes. Balled and burlapped trees and shrubs Protect trees from critter damage: come with burlap around the soil ball that Create a tube around the tree’s trunk is held together by a wire basket. These trees are often more mature than bare root using ¼ inch hardware cloth to protect it from critter damage. Extend the cloth at and containerized trees. least 3 feet up, and don’t let it touch the Remove the wire and burlap from the top tree. Make sure hardware cloth is on your of the soil ball to check for excess soil tree by late summer or early fall. Usually over the first main lateral root. Remove shrubs don’t need protection, but fencing excess soil if present. or hardware cloth around the shrub can prevent rabbit and vole damage. Use the same steps in the containerized section for determining the hole’s width Lauren Stufft, Undergraduate Research Assistant and depth. Be sure all of the burlap is Gary Johnson, Technical Advisor covered up when backfilling the hole. Jennifer Teegarden, Technical Advisor References: Moll, Gary. "The state of our urban forest." American Forests 95, no. 11/12 (1989): 61-64.
DRAMATICALLY INCREASE THE HEALTH & SURVIVAL OF TRANSPLANTED TREES
ALL YOU NEED TO KNOW ABOUT COMMUNITY GRAVEL BEDS University of Minnesota, Department of Forest Resources, 2013
Commonly Asked Questions What is a gravel bed and why would I build one? A gravel bed is an irrigated bed or pile of gravel to place and safely hold bare root or washed containerized stock for (a .k .a .“heeling in”) up to 3-6 months . Doing this dramatically increases fibrous root volume, decreasing transplant shock and increasing survivability of the plant . Since bare root stock is typically only available during spring, this also allows for staged plantings throughout the year.
Will this require a large upfront investment? Kentucky coffeetree from gravel bed Photo courtesy: Jacob Ryg
No, the price is up to you . You can use a pile of gravel you already have, or build a bed that is a centerpiece for your community.
Will using a gravel bed save my community money? Assuming you currently plant containerized or balled and burlapped stock, YES . Bare root stock is on average 1/4 the price of balled and burlapped, and 1/2 the price of a containerized tree . This along with the reduced planting cost and higher survival rates for trees planted in the autumn will add up to a significant savings .
Are there other communities in Minnesota currently using gravel beds? Yes, over 20 communities are currently using a gravel bed system with great success.
The gravel bed uses bare root stock. Aren’t they tough to handle? Wont they dry out? Bare root stock can dry out if not handled properly, but this can be easily prevented with proper covering while out of the ground . One of the advantages of using bare root stock is that it is much easier to transport and plant than alternative stock types . One person can plant with a shovel vs . using multiple people and machinery.
Would I be GROWING trees in the gravel bed? The above ground portion of the tree will not grow any faster than normal . The purpose is to increase the fibrous root system, recover poor root systems, and prepare for planting at a later date .
What if I buy bare root stock and don’t get them planted before winter? We do not recommend intentionally storing trees in a gravel bed over the winter, but as long as you protect the stems from critter damage, they typically do fine .
Can I put more than trees in a gravel bed and are there species that don’t do well? Yes, shrubs as well as most conifer and deciduous trees do great . The only species we know that struggle in a gravel bed are American linden and bur oak .
Is it difficult to find bare root stock of desired species? No, typically there are many more species available in bare root stock than balled and burlapped or containerized . See Appendix C for bare root suppliers .
Why not just plant bare root stock in the spring?
Swamp white oak from gravel bed Photo courtesy: Jacob Ryg
Most unfavorable weather for a transplanted tree occurs in spring and summer. By planting in the fall, roots have time to establish in more favorable conditions, allowing for a higher survival rate through the stressful times of the following spring and summer.
1
ALL YOU NEED TO KNOW ABOUT COMMUNITY GRAVEL BEDS
Community Gravel Beds A-Z A Community Gravel Bed (GB) is a system that has been in use at commercial nurseries, municipalities, and universities for over 20 years . Building one for your community can provide many advantages over planting traditional bare root, balled and burlapped, and containerized stock . The system is far from complex . All you are doing is placing bare root stock in an irrigated pile of gravel, which will increase the quality of the root system and prepare them for later planting . There are many communities in Minnesota that have built and are currently using the GB system with great success . Some of these community contacts are listed at the end of this document (Appendix C .) and you are encouraged to contact them about their experiences .
Before
After
bare root stock
14 weeks
Balsam Poplar
Balsam Poplar
Red Maple
Red Maple
Benefits of building a Community Gravel Bed Saving $ – The GB system uses bare root stock, which is on average ¼ the price of a balled and burlapped tree and ½ the price of a containerized tree . Ease of installation also increases savings because there are less people, time, and machinery required in planting bare root stock than alternative stock types .
Plant health and survival – An increased fibrous root system allows for an increased uptake of water and nutrients . Transplanting is a stressful time for any plant due to a high portion of its root system being lost when it is removed from the ground . The majority of the energy the plant produces is put into restoring lost roots and sustaining life . This reduces its available energy to fight off pests, diseases, and other health threats . The more water and nutrients the plant is able to absorb, the more energy it is able to produce for root restoration and defense . Planting times – In Minnesota, most of the unfavorable conditions for a newly transplanted tree occur in the spring and summer (wind desiccation, flooding, drought, etc) . This contributes to the difficulty of getting healthy trees established in an urban environment . By planting in fall, roots have time to establish in more favorable conditions, giving the tree a higher probability of survival through the more stressful times in the following spring and summer. Healing bare root trees and shurbs in a GB allows stock that is usually only available in spring to take advantage of these more favorable fall planting times . “Transplanting in early fall confers earlier post-transplant root growth and therefore is the best time of year to transplant most cold-hardy deciduous landscape trees .” (Harris, 2002) .
Volunteer Planting in Rochester, MN Photo courtesy: Jacob Ryg
Community involvement – Bare root trees provide excel- lent planting opportunities for volunteers due to their ease of handling and planting . A bare root tree can be planted by one person and a shovel . Plantings can be done quickly and efficiently by auguring holes with a machine and having a volunteer group follow behind planting and mulching . Using volunteers for tree planting is a good way to spark interest from community members to become stewards of your urban forest .
Better species availability – Typically there are more species available in bare root stock than in balled and burlapped or containerized stock . This allows for more diversity in your urban forest, reducing your vulnerability to pest and insect threats .
ALL YOU NEED TO KNOW ABOUT COMMUNITY GRAVEL BEDS
3
Volume discounts – When buying bare root stock for the GB, you are typically buying trees in high quantities . Often, this offers an opportunity to receive a discounted price . Recover pot-bound trees – A GB can be used to recover trees with pot-bound or substandard root systems . Trees with these issues can often be bought at a reduced price . The root system can then be recovered in the GB and planted out in better condition . The rooting structure is visible – Stem girdling roots are proving to be a significant problem with transplanted balled and burlapped and containerized trees . This is due to the difficulty and time needed to inspect the root systems for encircling roots on these stock types . Planting bare root stock allows you to easily examine the root system before installation, as well as identify the first main lateral root, assuring correct planting depth .
Sizing your Gravel Bed How many trees will you plant per year? What stem caliper of trees will you plant? After answering those questions, you can use the table to the right (Table 1 .) to determine what size GB will meet your needs . Example: to plant 50 trees that will average 1 .5”-2” in stem caliper, a bed measuring at least 10’x20’ will be needed .
Table 1. Sizing of gravel bed.
Picking a site to build a Gravel Bed Accessibility – Irrigation is an essential component of the GB . Easy and continuous access to water is a priority when deciding where to place the bed . Ability to drive close to the bed with a machine or vehicle should also be taken into account . Drainage – Do not choose a low lying area or a site that regularly has standing water after rainfall . Root growth will be inhibited by insufficient drainage . Keep in mind, the majority of the drainage does not take place vertically (through the soil), it takes place horizontally out of the bed . Knowing this, it does not matter if it is placed on an impervious surface, as long as water does not pool and it can drain out of the bed . Light and wind exposure – Light exposure is not crucial to the success of the GB . Shady sites have been used with no problems . Placing the bed on a site with high wind exposure can lead to uprooted trees in the GB . Sites with high wind and sun exposure will require more watering than sites with less exposure . Vandalism – If vandalism is a problem in your community, consider building it inside a fenced property or placing a fence around the GB . Alternative uses for area – It is not recommended to place a GB on a piece of land that might have another better use . Consider what the land could be used for in the future . This may dictate what style of gravel bed you build . Visibility – Placing the GB on a site that is highly visible to your community can be a good opportunity to educate community members and spark interest in volunteer efforts .
Types of gravel A gravel depth of at least 15” is needed throughout the bed . It is recommend to use 3/8” washed river gravel or 3/8” washed river gravel with 10% sand, some communities in Minnesota have used other media with great results . These mediums consist of: • • • •
3
3/8”washed river gravel Peastone and 10% fine sand Peastone and 10-30% TurfaceR “B” stone (3/4” washed gravel) with 20% fine sand
ALL YOU NEED TO KNOW ABOUT COMMUNITY GRAVEL BEDS
Adding sand or TurfaceR will increase moisture holding capacity and reduce the amount of watering needed, but may not be best for all species of nursery stock .
Building materials Required materials depend on the style of GB you plan on building . Do whatever is the most cost effective and works best for your community. If you desire a strictly utilitarian or temporary GB, consider just using a pile of gravel contained by some sort of barrier (such as “Jersey” barriers found in road construction Figure 2 .) . If you want to display the GB to your community, you might want to build it out of treated lumber and construct a sign stating its value to the community. Consider asking for donations of lumber or gravel from local businesses . Be creative . A GB can be constructed on a very modest budget .
Styles of Gravel Bed Building a traditional gravel bed with treated lumber (Figure 1.) This is a GB with all sides built of treated lumber and 4”x4” posts buried in the ground . Below is a materials list for this style (Table 2 .) .
Figure 1. This community gravel bed is 32’x16’ is located in Hendricks, MN. It was constructed in 2010 at a community park. It is made of treated lumber and is irrigated with a soaker hose.
Table 2. Materials list for traditional gravel bed with treated lumber.
ALL YOU NEED TO KNOW ABOUT COMMUNITY GRAVEL BEDS
4
Building a gravel bed with portable barriers (Figure 2.&3.) If you have a site you might want to repurpose in the future or want a strictly utilitarian GB, this may be a good choice for you . Figure 2 (right). This is a 70’x 50’ community gravel bed located in Rochester, MN. It is built on asphalt located at the Olmsted Country Fair Grounds. It has gravel about 30” deep contained by “Jersey barriers” and is irrigated with spray heads mounted on tripods. The gravel bed has been in use since 2010.
Figure 3 (left). This community gravel bed is located in Bemidji, MN. It was made of concrete blocks in 2011 and has one open side for machine access. Figure 4 (below). This is a 20’x50’ community gravel bed located in Fargo, ND. It was constructed in 2006 out of concrete and slopes to a 4” drain on one side. As you can see, it is easily accessed with a front end loader.
Building a permanent gravel bed out of concrete (Figure 4.) This is one of the most expensive options, but offers a good opportunity to recycle water that drains through the gravel as well as protection from damage by machinery while installing/harvesting plants from the bed . It is essential to have adequate drainage with this system, if the bed holds water it can be fatal to trees and shrubs .
A gravel bed without containment (Figure 5.) If a lot of space and a machine to move the gravel is available, this can be the easiest way to start a gravel bed .
Figure 5 (left). This gravel bed is located at Jim Whiting’s Nursery in Rochester, MN. It is 32,000sf and regularly holds 1,500 trees. They use a stationary spray head(SenningerR Mini-WobblerR) for irrigation. This gravel bed was built on soil and has been in operation since 1997.
5
ALL YOU NEED TO KNOW ABOUT COMMUNITY GRAVEL BEDS
Irrigation of Gravel Bed There are many options for GB irrigation . Make a decision based on what you already have and what is most user friendly for your situation . Irrigation timers (Figure 6.) Setting your irrigation system on a timer is the easiest and most reliable way to assure your GB is being watered regularly. A home grade irrigation timer works well . Soaker hose (Figure 7.) These offer easy installation and removal along with a lowered water usage due to minimal evaporation . Instances of rodent damage to soaker hoses have been reported in dryer months .
Figure 6. Irrigation timers.
Drip tape While practical for nursery â&#x20AC;&#x153;rowâ&#x20AC;? style plantings, this option is generally not recommended for gravel bed use . This is due to its labor intensive setup, short service time, and high vulnerability to animal damage . Stationary spray heads (Figure 8.&9.) These require less water pressure than a soaker hose, but use more water due to higher evaporation . Placing the spray heads closer to the ground decreases water use compared to heads higher above the ground . Irrigation time A good starting point for irrigation time is around 100 minutes of irrigation per day. Most home grade irrigation timers have 4-6 timing intervals you can set . This means you could do 4 intervals at 25 minutes, 5 intervals at 20 minute, and so on . It is recommended one interval during the night, one right before sun-up and the rest spread out through the daylight hours . These times are dependant on the flow rate of your system, along with the exposure of your gravel bed . Do not take these recommendations as law! Check the moisture of your bed and adjust accordingly.
Figure 7. Wrap soaker hose through rows of trees, placing it close to tree stems.
Figure 8. Stationary spray head.
Figure 9. Stationary spray head.
ALL YOU NEED TO KNOW ABOUT COMMUNITY GRAVEL BEDS
6
Installing bare root stock in the Gravel Bed Plan to install the bare root stock in the GB the same day it is delivered or picked up . If not, you can leave them overnight in a stock tank full of water, or in a dark cool place with wet straw or untreated burlap over the roots .
There are two options for installing stock into the GB: 1. With a shovel (Figure 11.) With the bed full of gravel, dig a trench down to ground level . Hold the trees in place and backfill the gravel on the root system and around the stem . Mound the gravel around the stems to hold them in place . Make sure to thoroughly water the stock in the gravel bed after installation and assure the irrigation system is working properly. Roots need to be covered with about 4 inches of gravel for stable moisture content .
Figure 11 (above). Installing trees in gravel bed with shovel.
2 . With a machine (Figure 12) If you have a machine with a bucket, start with a layer of gravel 2â&#x20AC;?-4â&#x20AC;? on the ground and the rest removed . Hold a row of trees upright and dump a bucket of gravel on the root systems . Dump enough gravel to hold the trees in place and move on to the next row. Make sure to thoroughly water the stock in the gravel bed after installation and assure the irrigation system is working properly. Roots need to be covered with about 4 inches of gravel for stable moisture content . Rows of installed trees, Rochester, MN Photo courtesy: Jacob Ryg
Monitor trees-The most important thing to monitor after tree installation is sufficient gravel moisture . Check the gravel bed regularly after installation and make adjustments to irrigation system as needed . As long as there is proper drainage in the bed, it is better to overwater than underwater.
Figure 12. Installing trees with a machine in Rochester, MN Photo courtesy: Jacob Ryg
Keeping roots from drying out before installing in GB. Photo courtesy: Jacob Ryg
7
ALL YOU NEED TO KNOW ABOUT COMMUNITY GRAVEL BEDS
Buried Root Systems and Tree Health By Gary Johnson
Tree snapped at SGR compression point below ground.
Above-ground stem girdling roots
Reprinted from the Minnesota Shade Tree Advocate, Volume 3 Number 4 Stem girdling roots (SGRS) are those roots that grow either partially or completely against and compress (girdle) stem tissues of trees. Xylem and phloem (conducting) tissues in the stems become much smaller in diameter at the point/s of compression, compromising the transport of water, nutrients and photosynthates ("food"). Trees become stressed and more vulnerable to secondary problems (drought, insect attacks). Often, the compressed areas of the stems are weak points and far too often are the points of failure during windstorms. For instance, in the catastrophic windstorms of 1998 in Minnesota, 73.3%* of the lindens that were lost actually broke at compression points from SGRS, and most broke below ground. SGRs can and do form above ground, especially with maples and poplars. However, they can develop on most species below ground and out of sight. How can this happen? If a tree's root system has been buried too deep, the stem is subsequently buried. When root systems are buried too deep - with some trees, that's one inch of soil over the first, main order (first branch) roots - secondary woody roots grow upward, closer to the soil surface. Often, some of these roots end up growing against the stem tissues, either partially or completely encircling the stems. Since 1997, the University of Minnesota Forest Resources Department has randomly sampled 303 trees (ash, maple, linden). Depths of soil over the first roots ranged from 0 to 13 inches. Analysis of the data later revealed a statistically significant relationship between depth of soil over the roots, condition of the trees and the frequency of stem girdling roots. As more soil was added over the root systems of those trees - for whatever reason - stem conditions declined and the frequency of stem girdling roots increased. So, deeper (planting) is not better. In the long run, it's worse for the long-term health and stability of the trees. *Based on the storm damage research conducted by the Department Forest Resources, University of Minnesota, 1995-present.
Dysfunctional root system - Apple tree failed in a wind storm
Poor stem condition related to stem girdling roots and excess soil over root system.
Early fall color is a sign of potential root problems
Strong Winds – Weak Trees – Lots of Debris Gary Johnson, Eric North University of Minnesota, Department of Forest Resources July 25, 2013 On June 21, 2013, the perfect storm swept through much of the southern two-thirds of Minnesota. In that path, community tree canopies were ravaged to different degrees with some communities only slightly damaged while others lost years of chlorophyll, shade in the summer and relief from winds in the winter. Unfortunately, many of those trees did some damage to sidewalks, curbs, cars, houses and utility lines on their way down. One month later, many communities and tree care companies are still scrambling to clean up the debris and begin the recovery process and once again there are those wondering if this damage could have been prevented. The Storm Failure Triangle© It’s rare when one single event with one single force is the sole reason for all of the damage to trees. Tree damage typically ranges from a few broken branches to trees uprooted and blown to the next county with loading events ranging from 25-30 mph wind storms to raging winds accompanied by heavy rains or ice. When tornadoes sweep through an area, trees affected are often innocent bystanders than they are bad trees fraught with weaknesses or architectural problems. More commonly, trees that topple range from dense-canopied evergreens in windswept landscapes with water-soaked soils to majestic and mature shade trees perched in narrow boulevards. The Storm Failure Triangle summarizes the main components of a weather loading event that result in some degree of damage by categorizing them as either: 1. The loading event 2. Site characteristics 3. Tree condition and any defects
Loading event: Any weather event that puts an unusual strain on a tree’s architecture or stability. Loading events range from a common thunderstorm with winds greater than 25-30 mph to 130 mph down-bursts or tornadoes. Events may also include the weight of rain, ice or snow. The greater the loading on a tree, the greater the potential for damage or failure. Unfortunately, there is no control over loading events but some damage can be lessened by avoiding planting or locating trees that are more vulnerable to some common loading events such as ice storms. However, avoiding tornadoes is out of the picture. Site characteristics: These include soil types, wind exposure or protection (friction), soil profile and saturation level, root plate space (narrow boulevard versus expansive lawn), plant competition. There is some level of control in this category; the most notable is to avoid planting high density trees in open areas that have chronically saturated soils. Or, avoid planting trees that mature at a height of 60 feet in boulevards that are four feet wide. Tree condition and defects: Often the most obvious and include size, presence and extent of decay, abnormal lean, included bark branch attachments, codominant leaders, canopy density, presence of static or dynamic cabling systems, live crown ratio, stem girdling roots, restricted rooting space, root loss due to construction activities and die-back. This is the category with the greatest opportunity to mitigate much of the damage and failures that result from storms. Early and regular can minimize architectural defects. Placing trees out of harm’s way or protecting trees from unintentional vandalism, string trimmers or lawn mowers can reduce the frequency and extent of decay. Avoiding planting trees genetically prone to decay or poor architecture in high risk areas may not reduce the risk of damage or failure at the tree level but will reduce the frequency of damage to people and property. Failure potential: The likelihood that the tree will fail or incur some degree of damage. The more loading on a tree, the more site characteristics that compromise a tree’s stability, health or condition and the more defects impacting a tree, the more likely failure or damage will result and the greater the severity.
The June 2013 Storm The storm that swept through Minnesota on June 21 was not all that unusual. Straight-lined wind storms may not be very predictable here but they are not unexpected when the humid, warm days of summer arrive. June 21 was a bit unusual in the respect that the high winds (60 mph and greater) were accompanied by soaking rains (2.5 to more than 7 inches). Saturated soils, sandy through clayey, offered less friction and anchorage potential for the tree roots. A perfect storm. Since 1995, the University of Minnesotaâ&#x20AC;&#x2122;s Department of Forest Resources has led the collection of storm damage data to trees as a result of loading events. When the storms hit Minnesota, two teams of researchers hit the streets and collected as much information as possible that related to the types of damage, the size and species of trees damaged and the site conditions. Damage was assessed in urban forests from Morris to the metro. Although not all data has been entered and analyzed, some familiar trends were revealed. 1. There was a high rate of complete failures, e.g., full or partial wind-thrown trees. 2. Most of the complete failures were attributed to (other than the high winds) saturated soils, dense-canopied trees, and trees with compromised root plates.
3. The same defects (consistently since 1995 when the research started) showed up in most of the abnormal failures or damages incurred by the trees: decay, included bark in branch attachments, and codominant leaders. 4. Small trees fared better than larger trees. 5. Boulevard trees failed more frequently than lawn or park trees. 4. Spruce and other dense-canopied conifers were over-represented in the complete failure categories.
Information is still being collected and there could be as many as 3,000 + trees evaluated this summer, significantly adding to the robustness of the conclusions drawn about damage and failure potentials. More importantly, lessons learned about mitigating some of the damage and failures will help both communities and property-owners avoid some of the monetary and environmental losses in the future. At the conclusion of the 2013 season and analysis of all data collected, a summary article will be posted that will include some suggested management practices that reduce these losses to boulevards, parks and lawns.
Tough Trees and Shrubs for Tough Sites By Gary R. Johnson, Mike Zins and Marc Shippee Copyright Š 2001 Regents of the University of Minnesota. All rights reserved.
Successful landscapes begin with the selection of plant materials appropriate for the site conditions. This fact sheet is designed as a reference guide to woody plant materials that tolerate tough sites. Recommendations are made for trees and shrubs that survive better than others in the following soil and site conditions: poorly drained soils, droughty soils, alkaline (high pH) soils, compacted soils and sites exposed to deicing salts. Detailed descriptions for each of these conditions are provided on the next page. The map shows the six major ecoregions in Minnesota. Minnesota's Ecoregions 1. 2. 3. 4. 5. 6.
Southeast Central Northeast North Central Northern Tallgrass Prairie Southwest
Tough Site Categories Poorly Drained Soils. A well-drained landscape soil should drain a 24-inch column of water in 24 hours or less. To determine if your site is well-drained, conduct a percolation test by auguring or digging a hole 24 inches deep. Fill the hole with water and allow to drain completely. Fill the hole with water a second time soon after the first filling is completely drained. The second filling should take 24 hours or less to completely drain. If the hole still contains water after 24 hours, it is considered poorly drained . . .to some degree. Droughty Soils . These soils are characterized by excessively rapid percolation rates (24 inches of water drains in a few minutes or less), and a low organic matter content(<1%) that can be determined by a lab soil test. Alkaline Soils . An alkaline soil will have a pH greater than 7.0. Most trees perform best in acidic soils(<7.0) to slightly alkaline (7.5). Compacted Soils. This is primarily a problem with fine-textured soils (clays, silts). Compaction may be gauged with a penetrometer or with a digging spade. If a spade easily penetrates the soil to a depth of two spade blades (about 18 inches), the soil is not compacted. If the hole needs to be dug with a pick axe, it's a compacted soil. Soil compaction will result in stressed plants, performing less than ideally and more likely to suffer from secondary problems such as diseases and insect pests. Deicing Salts. Deicing salts damage plants in two forms: accumulation of deicing salt run-off in the landscape soil, and drift of deicing salt spray. Salt spray damage is the most widespread and troublesome in Minnesota. Trees and shrubs within 60 feet of high-use roads are most at-risk for this type of damage. Native trees and shrubs are coded 1 - 6, following their name, to match the ecoregion/s where they are native. Bold lettering indicates an evergreen species. Y= yes, I= intermediate, S= sometimes.
Large Trees (over 60 ft.) Common (Scientific) Name Balsam Fir (Abies balsamea)
Ecoregion
Poor Droughty Alkaline Compacted Salt Drainage
1234
Black Maple (Acer nigra)
16
Red Maple (A. rubrum)
12346
Y Y Y
S
Y
Y Y
'Green Mountain' Sugar Maple (A. saccharum 'Green Mountain')
123456
Silver Maple (A. saccharinum)
12346
Yellow Birch (Betula alleghaniensis)
12346
River Birch (B. nigra)
123456
Paper Birch (B. papyrifera) 1 2 3 4 6 Bitternut Hickory (Carya 12346 cordiformis)
Y
Y
I
Y
I
Y
I (spray)
I Y
Y
I
Y I
Y
I
American Chestnut (Castanea dentata)
Y
Northern Catalpa (Catalpa speciosa)
I
Y
Y
Y
Y
Y
Y
I
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
I
I
I
Y
Common Hackberry (Celtis occidentalis)
123456
Y
White Ash (Fraxinus americana)
12
I
Green Ash (F. pennsylavanica)
123456
Y
Ginkgo (Gingko biloba) Kentucky Coffeetree (Gymnocladus dioicus)
16
Black Walnut (Juglans 123456 nigra) Tamarack (Larix laricina) 1 2 3 4 European Larch (L. decidua) Norway Spruce (Picea abies) White Spruce (P. glauca) 1 2 3 4 5 Colorado Spruce (P.
12345
Y
Y
Y
Y
Y
I
Y
Y
Y I
I
Y Y
pungens) Ponderosa Pine (Pinus ponderosa) Red Pine (P. resinosa) London Planetree (Platanus x acerifolia)
I 123
Y I
I
Eastern Cottonwood (Populus deltoides)
123456
Y
Y
Bigtooth Aspen (P. grandidentata)
123456
I
I
White Oak (Quercus alba) 1 2 4 6 Swamp White (Bicolor) Oak (Q. bicolor)
1246
Northern Pin Oak (Q. ellipsoidalis)
123456
Y I
Y
Y
Y (soil)
Y
I (spray)
Y Y
Eastern Pin Oak (Q. palustris)
Y
I
Y
Y
12346
Y Y
White Willow (Salix alba)
Y 123456
Littleleaf Linden (T. cordata)
I
Y (soil)
Y
Y
American Linden (Tilia americana)
I
I
Bur Oak (Q. macrocarpa) 1 2 3 4 5 6
Red Oak (Q. rubra) Black Locust (Robinia pseudoacacia)
I
Y
Y
I
Y
I
I
Y
Y
I
I
Y
Y
Y
Y
Y
Canadian Hemlock (Tsuga canadensis)
123
Y
American Elm (Ulmus americana)
123456
Y
I
I
Medium Trees (26-50 ft.) Common (Scientific) Name White Fir (Abies concolor) Hedge Maple (Acer campestre)
Ecoregion
Boxelder (A. negundo)
Poor Droughty Alkaline Compacted Salt Drainage I
123456
I
Y
Y
Y
Norway Maple (A. platanoides) Ohio Buckeye (Aesculus glabra)
I
Black Alder (Alnus glutinosa) White Alder (A. incana) Gray Birch (Betula populifolia)
Y Y
Y
I
Y
Y
16
Blue Ash (Fraxinus quadrangulata)
I
Y
Y
I
Y Y
I
Y
Y
I
Y
Y
Y
I
Y
Y
Y
I
I
Y
Y
Honeylocust (Gleditsia triacanthos)
1
I
Y
Y
Y
Eastern Red Cedar (J. virginiana)
12456
I
Y
Y
I
I
Y
Y
Y
Common Mulberry (Morus alba tatarica) Ironwood (Ostrya virginiana)
123456
Y
Y
I
Y
Y
I
Amur corktree (Phellodendron amurense) Black Hills Spruce (Picea
Y
Y
Y
Y
Turkish Filbert (Corylus colurna) Cockspur Hawthorn (Crataegus crusgalli) Downy Hawthorn (C. mollis)
I
I
I
Y
Y
I
I
Y
glauca densata) Black Spruce (P. mariana)
1234
Y
Serbian Spruce (P. omorika) Jack Pine (P. banksiana) 1 2 3 4
Y
Y Y
Austrian Pine (P. nigra) White Poplar (Populus alba)
Y Y
Y
Y Y 123456
I
I Y
I
Y
I
Common Chokecherry (Prunus maackii) Pin Cherry (P. pensylvanica) Chestnut Oak (Quercus prinus)
I 123456
Y
I Y
Chinkapin Oak (Q. muhlenbergii)
Y
Y
Black Willow (Salix nigra) 1 2 3 4 6
Y
I
Y
Laurel Willow (S. pentandra)
Y
I
Y
European Mountainash (Sorbus aucuparia)
Y
Y (spray) Y
Showy Mountainash (S. decora)
1234
Y
I
I
Northern White Cedar (Thuja occidentalis)
1234
Y
I
Y
Y
Y
Siberian Elm (Ulmus pumila)
Y
I
Swiss Stone Pine (P. cembra)
Quaking Aspen (P. tremuloides)
Y
Y
I
Small Trees (under 25 ft.) Common (Scientific) Name Amur Maple (Acer ginnala)
Ecoregion
Poor Droughty Alkaline Compacted Salt Drainage S
Tartarian Maple (A. tartaricum) Allegheny serviceberry (Amelanchier laevis) Speckled Alder (Alnus rugosa)
12346
I
123456
Y
Eastern Redbud (Cercis canadensis)
Y
Y
Y
Y
Y
Y Y (spray) Y
I
American Yellowwood (Cladrastis kentukea)
Y
Y
Y
Pagoda Dogwood (Cornus 123456 alternifolia)
I
I
American Smoketree (Cotinus obovatus)
I
Y
Russian Olive (Elaeagnus angustifolia)
Y
Y
Y
Chinese Junipers (Juniperus chinensis)
Y
Y
Y
Amur Maackia (Maackia amurensis)
Y
Y
Y
Y
Crabapple (Malus sp.) Prairie Crabapple (M. ioensis)
1
Bristlecone Pine (Pinus aristata) Waferash (Ptelea trifoliata) Ussurain Pear (Pyrus ussuriensis) Peachleaf Willow (Salix amygdaloides) Pekin Lilac (Syringa
I
Y
Y
Y Y Y
Y Y
123456
Y
Y
Y Y
Y
Y
Y
Common (Scientific) Name
Ecoregion
Poor Droughty Alkaline Compacted Salt Drainage
reticulata) Japanese Tree Lilac (Syringa reticulata)
Y
Y
Y
Y
Large Shrubs (12-20 ft.) Common (Scientific) Name Ecoregion
Poor Droughty Alkaline Compacted Salt Drainage
Korean Barberry (Berberis koreana)
Y
Y
Siberian Peashrub (Caragana arborescens)
Y
Y
Y
Y
Sea Buckthorn (Hippophae rhamnoides)
Y
Y
Y
Y
Mugo Pine (Pinus mugo)
I
Y
Y
Y
Smooth Sumac (Rhus glabra) 1 2 3 4 5 6
Y
I
Y
Y
Staghorn Sumac (Rhus typhina)
123456
Y
I
Y
Y
Scarlet Elder (Sambucus pubens)
123456
Y
I
Common Lilac (Syringa vulgaris) Nannyberry (Viburnum lentago)
123456
I
Y
I
I
Y
Y
I
Y
Medium Shrubs (6-12 ft.) Common (Scientific) Name Ecoregion fruticosa) Russian Peashrub (Caragana frutex) occidentalis)
12456
12
Poor Droughty Alkaline Compacted Salt Drainage Y
Y
Y
Y
Y
Y
I
Y
Y
I
Drainage
Medium Shrubs (6-12 ft.) cont. Redosier dogwood (C. sericea)
123456
American Hazel (Corylus americana)
12345
Y
12345
Y
Beaked Hazel (C. cornuta) Burning Bush (Euonymus alatus) Eastern Wahoo (E. atropurpureus) Common Witchhazel (Hamamelis virginiana)
12
Winterberry (Ilex verticillata) 1 2 3 4
Y
I
I
Y
I
Y
Y
S
I
Y
Y
Y
Y
Y
I
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y
Y Y
American Fly Honeysuckle (L. xylosteum) Y 123
Y
Y
Cherry Prinsepia (Princepia sinensis)
Y
Fragrant Sumac (Rhus aromatica)
Y
Rose acacia (Robinia hispida)
Y
American Elder (Sambucus Canadensis)
123456
Silver Buffaloberry (Shepherdia argentea)
56
Ural Falsespirea (Sorbaria sorbifolia)
Y
S
Savin Juniper (J. sabina) Tatarian Honeysuckle (L. tatarica)
Mockorange (Philadelphus sp.) Common Ninebark (Physocarpus opulifolius)
Y
Y Y Y
Y
Medium Shrubs (6-12 ft.) cont. Common (Scientific) Name Ecoregion
Poor Droughty Alkaline Compacted Salt Drainage
Vanhoutte Spirea (Spiraea x vanhouttei)
I
Chinese Lilac (Syringa x chinensis) Tamarisk (Tamarix ramosissima) Northern White Cedar (Thuja occidentalis) Shrub forms
Y
Y
Y
Y
Y
Y
Arrowwood Viburnum (Viburnum dentatum)
1
Y
Y
I
Y
Y
Y
Y
Wayfaringtree Viburnum (V. lantana)
Y
Small Shrubs (under 6 ft.) Common (Scientific) Poor Ecoregion Droughty Alkaline Compacted Salt Name Drainage Bearberry 1235 Y (Arctostaphylos uva-ursi) Black Chokeberry (Aronia 123 melanocapa)
S
Y
Japanese Barberry (B. thunbergii)
Y
New Jersey Tea (Ceanothus americanus)
Y
Sweet Fern (Comptonia peregrina)
Y
Cotoneaster sp.
Y
Daphne (Daphe x burkwoodi 'Carol Mackie') Dwarf Bush-Honeysuckle (Diervilla lonicera) Leatherwood (Dirca palustris)
Y Y
Y
Y
Y Y 12346
Y
Y
Y Y
Y
Common Juniper (Jumiperus communis)
123456
S
Y
Y
Y
I
Shore Juniper (Juniperus conferta)
Y
Y
Y
I
Creeping Juniper (Juniperus horizontalis)
Y
Y
Y
I
Labrador tea (Ledum groenlandicum) Sakhalin Honeysuckle (Lonicera maximowiczii sachalinensis) Northern Bayberry (Myrica pensylvanica) Bush Cinquefoil (Potentilla fruticosa) Western Sandcherry
Y Y Y (spray)
Y Y
Y
Y
I
Y
(Prunus besseyi) Sandcherry (P. pumila) trilobata)
Y Skunkbush Sumac (Rhus Y Y Y
I
Alpine Currant (Ribes alpinum)
Y
I
Rugosa Rose (Rosa rugosa)
Y
Bumalda Spirea (Spiraea x bumalda)
Y
Snowberry (Symphoricarpos albus)
S
Y
Y
Y Y Y
Y
Y
Coralberry (S. orbiculatus) S Y Lowbush blueberry Y I (Vaccinium angustifolium) Authors: Gary R. Johnson is an associate professor of urban and community forestry in the Department of Forest Resources, College of Natural Resources, University of Minnesota. Mike Zins is an associate professor of horticulture in the Department of Horticultural Sciences, College of Agricultural, Food, and Environmental Sciences, Unviersity of Minnesota. Marc Shippee is the city forester for Blaine, Minnesota.
Partial funding was provided by: Minnesota Shade Tree Short Course
MINNESOTA DEPARTMENT OF TRANSPORTATION
2013 Landscape Inspection Manual
Tree & Nursery Stock Selection Criteria
This document focuses on the rights and responsibilities of consumers and those in the nursery trade. It is meant to help the “consumer” better determine health of plant stock and (when specified) outlines the minimum requirements set out by ANSI Z60.1 . MnDOT may require a higher standard than set by ANZI when conducting business with its contractors in some cases. Some of these “higher standards,” though not governed by law are widely considered “best practices”. -Minn. T.I. Program
Additional manuals are available for sale by the Map and Manual Sales Office, Room 110, State of Minnesota, Department of Transportation, 395 John Ireland Blvd., M.S. 260, St. Paul, MN 55155. Call 651-366-3017 to request an order form. The price is $12.00, plus State Sales Tax (when appropriate), plus handling and postage. Checks, drafts, or money orders, made payable to the Commissioner of Transportation, must accompany all order forms. Upon being published and made available for distribution by the Minnesota Department of Transportation, this Manual shall become effective by reference in the Contract Plans, Specifications and/or Special Provisions. Acknowledgements American Standard For Nursery Stock, ANSI Z60.1 City of Minneapolis and St. Paul Forestry Staff Minnesota Department of Agriculture Plant Industries Division Minnesota Department of Natural Resources Division of Forestry Minnesota Department of Transportation (MnDOT) Environmental Planning & Design Unit Construction Office Roadside Vegetation Management Unit Maintenance Office Site Development Unit Specifications Unit Erosion Control & Bioengineering Unit Contract Administration Office Minnesota Nursery and Landscape Association Contractors and Suppliers University of Minnesota Departments of Forestry and Horticulture I hereby certify that the Inspection and Contract Administration Manual for MnDOT Landscape Projects, 2013 Edition, was prepared under my direct supervision and that I am a duly licensed landscape architect under the laws of the State of Minnesota.
DAVID P. LARSON License No. 24237 Dated: June 27, 2012 Phone: 651-366-4637 e-mail: david.larson@state.mn.us
Acknowledgements
INSPECTION AND CONTRACT ADMINISTRATION MANUAL FOR MnDOT LANDSCAPE PROJECTS, 2013 EDITION
Inspection & Contract Administration Manual for MnDOT Landscape Projects
2013 Edition
Plant Stock Inspection If transport and handling of plant stock are acceptable, inspect plants for compliance and acceptance either in the delivery truck or as they are unloaded. Accept only plants specified in the plan or preapproved substitutions that meet the health and vigor criteria for acceptance. Plant stock type and form are specified for each landscape project in two locations in the plan (see Appendix H): 1. Estimated Quantity Sheet specifies the Pay Item, Plant Type and Size, Unit, and Pay Item Quantity. 2. Plant Stock Tabulation Sheet specifies the Key name, Species name (Scientific and Common), Size, Type, Required minimum size, individual plant type quantities and spacing. Acceptance requirements for each plant stock type and form are described in this Manual beginning on page 4-12. Plant Stock Labels Reject plant stock without identification labels on all individually shipped plants and on all bundles, bales, flats, or boxes of plants. Plants are labeled by either a common or botanical name (or sometimes both), size, and quantity contained in the bale, flat, box, etc. Inspecting Roots Healthy plants begin with healthy roots. A combination of woody and fibrous roots Identification Label throughout a well-balanced root structure is necessary for proper water and nutrient uptake. A balanced root system spreads out and uniformly anchors the plant in an upright position. In the nursery, plant stock should receive consistent care and be periodically transplanted or root pruned to promote healthy and absorbing roots. The proper root depth is when the first order root is at or slightly above the soil line. *
Reject plants with undersized, insufficient, unbalanced, damaged, or improperly stored, transported or handled root systems. Unbalanced roots result in plants prone to being tipped or blown over and restricts moisture and nutrient supply.
*
Reject plants with encircling roots that cannot be properly repositioned during installation. Encircling roots (stem-girdling roots) over time may result in lack of vigor, uneven growth, or complete failure when blown over in high winds or when uptake of nutrients is cut off.
Balanced and One-Sided Roots
4-2
Accept and Reject Roots
Chapter 4: Initial Planting Operations
2013 Edition
Inspection & Contract Administration Manual for MnDOT Landscape Projects
Plants for MnDOT landscape projects are specified in one of four root systems that have the following specific acceptance criteria: Root Measurement Root Type
Measurement
Bare Root
Average root spread (in inches)
Container B&B
Width and depth of ball or container (in inches)
Machine Moved
Spade diameter (in inches)
Image
Bare Root (BR) Bare root plants have been dug while dormant and the soil has been removed from the roots. They are stored in cold storage at high humidity and can only be planted during the spring and fall dormancy periods. Bare root plants should have tight buds and not be leafing-out prior to planting. Fall planting is not allowed for the bare root form of the species listed below. However, if the Contractor requests conditional authorization from the Engineer to install the bare root form of these species during the Fall Installation Period, it will be at the Contractorâ&#x20AC;&#x2122;s risk and establishment period will not begin until the following spring. Birch Poplar Mountain Ash Hackberry Plum/Cherry Dogwood Chapter 4: Initial Planting Operations
Oak Honeylocust Russian Olive Willow Hawthorn Sumac
Crabapple Ironwood
Maple Linden
4-3
Inspection & Contract Administration Manual for MnDOT Landscape Projects
2013 Edition
Visually compare bare root stock to the following root form categories: *
The photographs represent acceptable root systems for the species and root form.
*
The minimum acceptance standard will be 25% less root mass than the photographs.
Non-Fibrous Fine More than 10% fibrous roots. Primary woody roots are small and numerous. Plants with Non-Fibrous Fine rooting include: Hawthorn Honeysuckle Black Locust Mugho Pine Boston Ivy Serviceberry Buffaloberry Quaking Aspen Catalpa Redmond Linden Crabapple Roses Elder Russian Olive Elm Plum Swamp White Oak Non-Fibrous Coarse Less than 10% fibrous roots. Primary woody roots are larger and less numerous than Non-Fibrous Fine. Plants with Non-Fibrous Coarse rooting include: American Linden Kentucky Coffeetree Red Oak
Bur Oak Ginkgo Poplar (hybrids)
Chokecherry Fir Pine Sumac
Fibrous Fine More than 50% fibrous roots. Primary woody roots are small and numerous, with a mop-like appearance. Plants with Fibrous Fine rooting include: Birch Euonymus Potentilla Spirea Bittersweet (vine)
Grape Vine Viburnum
Hydrangea Weigela
Mockorange Yew
Fibrous Coarse More than 10% fibrous roots. Primary woody roots are larger and less numerous than the Fibrous Fine form. Plants with Fibrous Coarse rooting include: Amur maple Cherry Dogwood Hackberry Juniper Maple Pin Oak Willow
4-4
Arborvitae Currant Honeysuckle Hazelnut Larch Ninebark Snowberry Woodbine
Ash Cotoneaster Englemann Ivy Honeylocust Lilac Peashrub Spruce Dwarf-bush Honeysuckle
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Inspection & Contract Administration Manual for MnDOT Landscape Projects
Balled and Burlapped (B&B) and Container Grown B&B plants are dug with soil remaining around the roots and the soil ball wrapped with burlap and usually a wire basket. Containerized plants have been grown in a container (plastic, metal, wood or paper-fiber). *
Reject plants with root flairs more than 4 inches below the soil line. Plants that are too deep in the ball or container may be deprived of adequate oxygen. MnDOT specifications allow acceptance of B&B and Containerized plants with less than 4 inches of soil over the root flare only if the excess soil can be removed and all other plant and installation requirements are met. Balled and Burlapped
Container Grown
Accept & Reject
When acceptance of B&B or Container material is in question, MnDOT may open soil balls or remove the container to inspect for root condition, size, balance, and trunk location within the ball. Reasons to open a ball include poor roots, lack of a root flare, roots on top of the ball or out of the container, or old decaying burlap. This inspection can take place in conjunction with the competency test, adjacent to a prepared planting hole so that if the plant does meet requirements, and is still intact, it can be planted. Root ball inspection shall verify that: *
The root flare is at the soil line or no more than 4 inches below the top of the soil line if the excess soil can be removed without damaging the plant.
*
Roots extend no more than 4 inches beyond the burlap or container.
*
Numerous larger diameter root stubs are not present.
*
Roots fill the soil ball.
*
The plant is no more than 10% off center in the soil ball, unless the ball is oversized allowing a centered plant within the minimum radius spread for the root types specified.
Chapter 4: Initial Planting Operations
Root Ball Inspection
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*
Treated burlap is vertically slit through any remaining burlap at the time of installation, at 6 inch intervals around the ball in a manner that does not damage the roots.
*
Containerized plants are not â&#x20AC;&#x153;pottedâ&#x20AC;?. Potted plants have not been grown in the container long enough to produce adequate new fibrous root growth to hold the soil ball intact when removed from container.
*
Soil balls are not broken or loose . Test by pulling on the stem or crown of the ball. If the stem or crown moves and the ball does not, the ball is broken. A broken soil ball indicates torn fine woody and fibrous absorbing roots which are necessary for proper water and nutrient uptake.
*
All plants are handled by the soil ball, not by the branches or trunk to avoid damaging the root ball and trunk.
*
Paper-fiber pots are slit vertically at six equidistant locations around the circumference and the top is removed to no less than 1 inch below the soil line at the time of installation.
Machine Moved (MM) Machine Moved trees are those that have been dug, transported, and transplanted with a hydraulic tree spade. MnDOT will specify machine moved transplanting to allow installation of large or salvaged trees and shrubs.
Machine Moved
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The minimum spade size requirement for machine moved transplants varies according to the plant size and species. Minimum Spade Size (Diameter)
Deciduous Trees (Caliper)
Oak Trees (Caliper)
Conifer Trees (Height)
42”
2”-3”
1”-1½ ”
5’-7’
60”
3”-4”
1½”-2½ ”
7’-9’
78”
4”-6”
2½”-3½ ”
9’-14’
85”
6”-8”
3½”-5 ”
14’-18’
Inspecting Top Growth Shoots Deciduous trees have growth rings created by the terminal bud along the twigs. Conifers have branch whorls. The space between each ring or whorl indicates one year’s growth (typically) in northern climates. In a year under moisture and temperature conditions which are very favorable for growth, plants which have a tendency to exhibit “free growth” (paper birch, poplar, apple, woodbine ivy, ginkgo, several types of maple & larch) may put on more than one flush of new shoot growth. *
Expect at least 4 inches of shoot growth for plants that have received good nursery care. For fast growing trees such as poplar, you may see 8-inches or more of growth.
*
Short spaces between shoot rings or whorls indicate a year when the plant was under stress. Short or stunted needles or smaller leaves also indicate stress.
*
Reject plants with shoots that are limp or wilted.
Evergreen Shoot Growth
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2013 Edition
Buds Check bud vitality on deciduous trees by splitting open one or two buds. Look for green tissue, which are the unopened leaves and/or flowers. *
Reject plants with shriveled, dried out, or dead buds. Dead buds may fall off when touched, brushed, or split.
*
Reject plants with new buds or candles that are limp or wilted.
Most healthy buds are plump. EXCEPTIONS-do not expect plump buds on hackberry, willow, or some of the smaller shrubs like spirea or potentilla. Kentucky coffeetree, and honeylocust buds are depressed or hidden in the twig and are not visible.
Spruce Candling Growth
Conifers should have tight buds and should not be candling (sending out new growth) prior to digging. Plants dug while candling or leafing-out are put under stress and the reduced root system that is dug and transplanted may not be able to support the new growth that began to elongate before digging.
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Inspection & Contract Administration Manual for MnDOT Landscape Projects
Wounds Examine the trunk, stem, and branches for wounds or bruises. These can provide an avenue for diseases and insects to enter and may increase the chance of sunscald and frost crack formation. Wounds are identified by discoloration or scraping of the bark. Trees are sometimes delivered with a protective sleeve of cardboard or plastic around the trunk and with the branches tied together. The sleeves and tied branches limit wounds to the trunk and branches during transport but they can also hide existing wounds. Cut the twine and remove the sleeve or slide it up to examine plants for damage. *
Reject plants with cankers; localized sunken, raised and discolored dead areas. Cankers usually form around a dead bud, branch, stub, or a stem wound.
*
Reject plants with frost cracks. Frost cracks are vertical cracks in the bark which occur in winter.
*
Reject plants with cracks or wounds caused by weed whips or mowers in the nursery.
*
Reject plants wounded through the outer bark during installation unless (Shigo method) can remedy the problem.
Wound
Chapter 4: Initial Planting Operations
Cankers
Frost Cracks
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One Good Tree
UNIFORM BRANCHING NO CROSSING OR RUBBING BALANCED FORM
GOOD BRANCHING ANGLE PROPER "DOUGHNUT" CALLUS, NO STUBS
PLANTED WITH ROOT FLARE AT GROUND LEVEL (PROPER DEPTH) NO WOUNDS
GRADE
UNIFORM _ ROOTS
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,
NO BROKEN OR DRY ROOTS AND ROOT HAIRS
Chapter 4: Initial Planting Operations
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Inspection & Contract Administration Manual for MnDOT Landscape Projects
One Bad Tree NO TRAINABLE CENTRAL LEADER BRANCHING ONLY ON ONE SIDE
IMPROPER CROSSED AND RUBBING BRANCHES
NO LABEL -- - LEFT BRANCH STUBS
CUT L ------INTO BRANCH
TIGHT ANGLE BRANCHING
COLLAR
LOTS OF -----=::::::--- FRESH (WHITE) CUTS
-
CIRCUMFERENCE WOUNDS
LARGE CUT
LARGE OR NUMEROUS SUCKERS GRADE ONE S DO ED TS - --------RIO
BROKEN ROOTS
---------JJ
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The Contractor shall prune dead, rubbing, damaged or diseased branches, and unwanted suckers and remove debris from the Project site. Following removal of diseased branches, disinfect tool before making next cut. Dead branches and stubs or crossed and rubbing branches create wounds that cannot completely close and seal off. Flush cuts (too close) also make it impossible for the wound to completely close. Wounds provide entry points for decay, insects, and disease. No more than 25% of the live canopy may be removed during one growing season. must produce clean cuts using the Shigo method and must not tear or crush branches. Scissor- type bypass pruners and saws shall be used. A bypass pole pruner may be used only during the PEP. Misuse of pole pruners may cause the central leader and/or branches to tear and cause rejection of the plant. Anvil pruners and hedge shears, which tear bark while crushing and bruising branches at the site of the cut, are not acceptable.
Scissor Pruners
Accepted
Photo credit: www.felco.com
Anvil Pruners
Saws
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Not accepted
Accepted
Hedge Shears
Not accepted
Pole Pruner
Accepted during PEP only
Chapter 5: Plant Establishment Period
2013 Edition Prune branches so that an outside bud becomes the new terminal bud. Trees with multiple leaders must be pruned to improve symmetry and to establish central leader dominance. For tree branches larger than 2 inches in diameter, the Shigo method is required. To prune by the Shigo Method follow the steps below. *
Cut part way through the branch at point A.
*
Cut completely through branch from point B to A.
*
Cut from point C to D.
*
Leave branch collar (C to D).
*
DO NOT flush cut (C to X).
*
DO NOT leave stubs (A to B). by Shigo Method
to Live Buds
Chapter 5: Plant Establishment Period
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Structural of Young Elms Dutch Elm Disease resistant Elms have gained in popularity and availability within the last few years. These trees are valued for their beauty, historical significance, fast growth and ability to tolerate a wide range of conditions. These American, Asian, Eurasian, and Hybrid Elms require special to achieve their iconic vase shape, especially during the first ten years. For detailed information on Young Elms, refer to â&#x20AC;&#x153; Young Elmsâ&#x20AC;? by Chad P. Giblin. More information is available at: trees.umn.edu
Steps for Structural o f Young Elm
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INCLUDED BARK
THIS BRANCH LACKS THE STRUCTURAL INTEGRITY REQUIRED OF LARGE SHADE TREES AND SHOULD BE REMOVED FROM THE CROWN
CUT
Steps for Structural P r u n i n g of Young Elm
Chapter 5: Plant Establishment Period
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1. The Storm Failure Triangle summarizes the three main components of a weather loading event that result in some degree of damage by categorizing them as either: the loading event, site characteristics or tree condition and any defects. A. True B. False
2.
Which of the following would be considered a loading event? A. A storm with severe straight line winds. B. Improper cabling or guying of tree limbs. C. Heavy ice or snow storms. D. All of the above. E. A and C.
3. A percolation test is a method people use to determine a soil’s ability to deal with drought or excessive water. In regards to this type of test, which statement below is most accurate? A. A well-drained landscape soil should drain a 24” column of water within 24 hours. B. A poorly-drained landscape soil can take up to 24 hours to drain a 24” column of water. C. Regarding soils, no “significant” information can be obtained using a percolation test. D. A well-drained soil should never take more than 12 hours to drain a 24” column of water. 4.
Who sets the MINIMAL legal nursery pot size that a 1 ½” caliper tree can be sold? A. The Minnesota Landscape and Nursery Association (MNLA) B. MnDOT Landscape Inspection Manual C. The Minnesota Shade Tree Advisory Committee (MnSTAC) D. The American Standard for Nursery Stock (ANSI Z-160.1)
5.
According to the 2013 MnDOt Landscape Inspection Manual, a root system made up of 50% fibrous roots would: A. Meet their minimum standard for coniferous shrubs. B. Be classified as a “fibrous fine” root system. C. Be excluded from planting in droughty sites or areas capable of receiving 12 or more hours of direct sun exposure in a 24 hour period. D. Both A and B
6. “Box cutting” is an extreme solution to correct encircling or girdling roots in pot -bound nursery stock and most often leads to tree decline or mortality. A. True B. False 7.
Which statement(s) below, accurately describe the benefit(s) of a community gravel bed? A. The community gravel bed is one option fiscally challenged communities can utilize to grow more trees. B. Fibrous root development, financial savings and ease of planting “bare root” stock types are three reasons many communities have adopted the gravel bed system. C. Adoption of the gravel bed system is one way to increase diversity of species in a community’s public tree population. D. All of the Above. E. Both B and C.
Section Quiz: Best Planting Practices (cont.) 8. According to the MnDot Landscape Contractor Manual, what is the greatest percentage of live canopy that can safely be removed during one growing season? A. 33% or less. B. 60% or less. C. 50 % or less. D. 25% or less. 9. When planting a balled and burlapped tree, you must remove the entire wire basket. Not doing so will likely kill the tree. A. True B. False
*Answers for all â&#x20AC;&#x153;Section Quizzesâ&#x20AC;? are located at the end of this manual.
Below is a list of supplemental materials. They are provided solely for individual study and reference. THESE MATERIALS ARE NOT COVERED IN THE 2014 TREE INSPECTOR EXAM. Supplemental Materials MnDot Landscape Inspection Manual: 2013 Edition American Standard for Nursery Stock, 2004 Edition All You Need to Know About the Community Gravel Bed, 2013 Edition Minnesota Tree Inspector Minnesota Forest Pest First Detector Program Minnesota Shade Tree Short Course
Links http://www.dot.state.mn.us/roadsides/vegetation/pdf/landscapeinspectionmanual.pdf
http://www.nj.gov/agriculture/divisions/pi/pdf/jgstandards.pdf http://trees.umn.edu/files/2013/11/All-You-Need-to-Know-About-Community-GravelBeds-2013-edition.pdf
http://www.mntreeinspector.com/ http://www.myminnesotawoods.umn.edu/forest-pest-first-detector/ http://www.mnshadetree.com/
Section Review Quiz Titles
QUIZ ANSWERS:
Firewood Identification and Regulations
1. 2. 3. 4. 5.
A A B D B
Dutch Elm Disease
1. 2. 3. 4. 5.
C C D C A
Oak Wilt
1. 2. 3. 4. 5. 6.
D C B A D A
Emerald Ash Borer
1. 2. 3. 4. 5. 6.
A D A C D B
Other Pests, Plants and Pathogens
1. 2. 3. 4. 5. 6.
B C C A E A
Best Planting Practices
1. 2. 3. 4. 5. 6. 7. 8. 9.
A E A D B A E A B