Vol. 13, No. 3
Feature Article
Urban Apples
By: Jeffrey Johnson
Selecting and Establishing Apple Trees in the Landscape. Part One. Goals and Objectives. Assess your goals and objectives in having apple trees. One must understand the substantial commitment and environmental costs of growing apple trees. Sometimes it is best to remove and replace an apple tree with a disease resistant flowering crabapple. Pomology - Fruit Science Pomology, the science of growing apple trees, manifests a system by which an orchard is planted and tended over many years (decades). The rootstock/cultivar combination, planting pattern and spacing, pruning and training system, nutrient management, disease and insect management, harvest methods and marketing integrate to pomology.
Autumn 2011
Jeffrey L Johnson Landscape Gardener Woody Plants Specialist
University of Minnesota:
Tree Fruit Basics: • Cultivar: An asexually propagated plant that has been selected for specific desirable characteristics. • Graft: A method of asexual plant propagation widely used in horticulture for the propagation of trees and shrubs. • Clonal rootstocks: plants with an established root system used for grafting a cultivar onto for uniformity of the properties imparted from the rootstock to the scion, such as dwarfness, precocity and disease resistance. •
Scion: Part of a cultivar grafted onto the rootstock and grown into a tree.
•
Precocity – the ability of a tree to bear fruit soon after propagation. Site Selection A critical concept of growing fruit is 'harvesting the sun'. Full sun is a must; at least 8 hours of direct sunlight. Fruit trees have a low tolerance to shade. This can be a major limitation, particularly in urban sites.
Minnesota Landscape Arboretum
Inside This Issue: Feature Article:: Urban Apples
1
Member Profile: Mark Schnobrich
2
? Mystery Tree ?
3
Tree City USA: Spotlight, Fergus Falls, MN.
3
Survivors and Champions
4
Clip and Save Pomology Harvesting the sun - Zestar Apples Photo Dave Hansen. Advocate • Autumn 2011
Continued on page 7
Contacts & Calendar Page 1
5 11
Member Profile
Mark Schnobrich
By: Rebecca Koetter
Approximately 32 years ago, a forestry star was released into the natural resource world from the University Of Minnesota: Mark Schnobrich. Mark began his career at the Minnesota Department of Agriculture, took a brief working stint at the Colorado Forest Service and finally came back to Minnesota to assume the City Forester position with the City of Hutchinson. Thinking he would be taking on only a short assignment in Hutchinson, he instead found that five years turned into 15 that turned into 32 years very quickly, and from that, a career was born. In those 32 years, Mark has had several challenges and rewards while working with the City and is so thankful for all those years. He has been very fortunate to have lived in a community filled with people who supported his position as a full-time forester and actually went along with some of his crazy ideas! If anything sticks out in his mind it is his memories of working with citizen volunteers, the tree board and pulling together several DNR Regional Arbor Day events. These were large events that took a lot of coordination of people and resources, a feat made somewhat easier with the help of the terrific people that were part of the program! The tree board was very active and filled with movers and shakers who really helped lead the City of Hutchinson to be an outstanding example of a green community. As the City of Hutchinson moves into the future Mark would like to see it looked upon as the standard for incorporating sustainable growth into prairies and rain gardens. Now that Mark has retired as the City Forester, he has begun another full time career as a Renaissance man of the Prairie! Forget fossil fuel engines and say hello to the cleanest engine requiring only water and corn- and no I am not speaking of ethanol. I am referring to four-legged animal power, aka draft horses. Mark has welcomed two draft horses to his home in rural Hutchinson. They can and will be used to help cultivate another of his past-times: commercial hazelnut production. Mark is developing a crop of hazelnuts with the help of UMN researchers such as Lois Braun, which will be used for promoting an alternative to industrial agriculture with a sustainable crop such as hazel oil and consumable hazel nuts. And since there may be an extra second or two in the day, Mark will also be doing some forestry consulting in his spare time. One final message that Mark wants to share with foresters now and into the future is that the UMN, DNR and organizations like MNSTAC have been crucial in keeping urban forestry a central focus in communities throughout the state, especially in small communities. These agencies and organizations are readily available and have considerable expertise so that when small communities find a champion to lead a project or effort they can take advantage of the fantastic resources found within these organizations! Photo provided by Mark Schnobrich
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Autumn 2011 • Advocate
Mystery Tree
Mystery Tree
By: Rebecca Koetter and Dave Hanson
A tree with feathery foliage providing dappled shade and a delicate appearance is before you. It may not be so inviting or innocent in its natural form due to the arming of its stem and branches. The tree is displaying pinnate compound leaves, but don’t be perplexed when upon closer inspection you discover them to be singly pinnate and/or doubly pinnate. Another common name for this species describes its sweet edible pods that cattle thoroughly enjoy when they are available. Any guesses as to the name of this mysterious tree?
Tree City USA: Spotlight
F By: Andi Deirich
ind the answer on Page 12.
Tree City USA
What is a Tree City USA: Spotlight? In an effort to raise awareness of the different urban forestry programs around the state, each Advocate issue will include one Tree City USA community that has developed a unique tool to enhance the visibility or sustainability of their program. If you would like to nominate a community for the spotlight, please send the name of the community and the contact information for a representative to Ken Holman at ken.holman@state.mn.us. Photo provided by Fergus Falls
Tree City USA: Spotlight- Fergus Falls, MN
Fergus Falls, a city of roughly 13,600 people, is the oldest Tree City USA community in Minnesota, a fact which still irks Minneapolis to this day! This community which can be found off 94 as you head to Fargo, ND, has the distinction of being not only the oldest Tree City USA Community in Minnesota, but also one of the first Tree City USA communities nationally.
Advocate • Autumn 2011
What makes this community so interesting? Its passion for natural resources. As the economy forces communities to let positions go, Fergus Falls still employs a full-time forester. Not only is the community proactive, the residents are engaged. One example of community engagement is a 2007 survey which was incorporated into the Fergus Falls comprehensive park, recreation and forestry plan. The survey was sent out with the expectation of only 300 responses, instead the city received a whopping 700 completed surveys. In addition to planting 300 trees in 2010, Fergus Falls keeps the latest information on pruning and planting accessible on its website. A unique feature they also included was a list of reasons why certain trees are not used (citing issues with deicing salt, sidewalk upheaval, and susceptibility to breakage). Keeping the public informed and Fergus Falls stays on top of their game. Page 3
The Survivors and Champions...
By: Dave Hanson
Another champion in the city! There are a number of river birch (Betula nigra) standing tall and proud in Tower Park of North Saint Paul. These trees, in particular the champion, definitely show signs of having been tested over the years. With several target cankers, a hollowing stem and several seams the champion has obviously weathered many storms. This tree is worth a visit. It is not often that a person can stand next to a river birch of this age to study its bark, its branches and its form. In coming issues we will try to visit other communities and other “Survivors.” If you know the location of a champion tree and would like it highlighted here send Dave Hanson a note (e-mail: dlhanson@umn.edu) and it is likely he will pay you and the champion a visit.
Photos taken in 2011.
If you have a tree that you would like to nominate or you are curious about the Minnesota Department of Natural Resource’s Big Tree Registry visit: http://www.dnr.state.mn.us/trees_shrubs/bigtree/index.html
The champion
Dave Hanson
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Autumn 2011 • Advocate
Hints for Success with Urban Apple Growing Planting All trees should be planted with the root flair at or less than ½” below final grade. Stem girdling roots are a concern with all trees, including fruit trees. http://www.extension.umn.edu/distribution/naturalresources/dd7501.html Support. Staking newly planted trees is a good idea for at least one growing season. As always, secure the tree trunk with a non-restricting soft material that allows some movement of the trunk. Depending on the rootstock, you may want to install a permanent support. Pruning and Training. Jeffrey Johnson’s Five Steps To Successful Pruning of apples: “San Struc Fram’s Clear Bal.” 1. Sanitation – 2. Structural – 3. Framing –
Dead, wounded, rubbing. Eliminate narrow branch angles. Separation vertically and radially.
4. Clearance – 5. Balance –
Early is better. Only as necessary with fruit trees. Unify density through selective thinning.
Other guidelines to successful pruning: • Respect the branch collar. • If no collar, “smallest wound without leaving a stub.” • Thin to significant branches or trunk no smaller than 1/3 the diameter of the branch you are removing • Thin a maximum of 1/3 of live wood per year.
Many orchardists use specialized space saving systems, including “Espalier,” “Hedgerow,” and “Slender Spindle”. These require a higher level of technical skill and knowledge. The goals of the system do not change however.
Photo: Espalier of Honeycrisp apple at the Minnesota Landscape Arboretum. Dave Hanson Continued on next page Advocate • Autumn 2011
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Hints for Success with Urban Apple Growing Disease and Insect Control. Disease and Insect control in an urban environment can be challenging and perplexing. If high quality apples are to be harvested consistently, your apple trees must be protected from fruit and foliar diseases and insects. This involves ‘cover sprays’ throughout the growing season or laborious methods of protecting the fruit (bagging). A cover spray is a protectant spray, applied before an insect or disease has a chance to infect or infest a tree or its fruit. Major Diseases: Apple Scab and Cedar Apple Rust Apple Scab and Cedar Apple Rust are fungal diseases requiring free moisture (droplets) on the surface for an extended period of time to infect the host. Both can cause defoliation and unsightly surface blemishes on the fruit. Sanitation and protectant fungicides are recommended to minimize these. Fireblight Fireblight is a deadly bacterial disease spread in humid weather from an active infection that oozes bacteria which is spread to vulnerable tissue such as fresh wounds, flowers, fruit or young growth. Some keys to controlling fireblight are sanitation, moderate vigor and reduction of injury to vulnerable tissue during warm humid weather. Major Insects: Codling Moth and Plum Curculio Early season insects (May through mid June in MN), they overwinters as pupa (cocoon) and emerges as the fruit develops after bloom. The adults breed and the female lays eggs on fruit, which hatch and tunnel into the fruit, feeding for a few weeks. The Codling Moth larvae exit the fruit, drop to the ground and spin a web to pupate. The fruit quality and storageability is greatly diminished from the larval feeding. Plum Curculio are snout beetles that cause damage to fruit at several stages of their life cycles. Adults feed on very young fruit; females ovipositioning eggs results in a crescent shaped scar. Usually in Minnesota, the early adult feeding and the crescent scars are the only damage seen. Cover sprays that control Codling Moth will usually result in good control of Plum Curculio. http://ohioline.osu.edu/hyg-fact/2000/2203.html http://ohioline.osu.edu/hyg-fact/2000/2043.html http://web3.canr.msu.edu/vanburen/plumcurc.htm Apple Maggot Apple Maggot is a fly emerging late June, at the earliest. The larvae, a true maggot, drop with apples from the tree to overwinter in the soil as pupae. After pupation and rainfall, the adults emerge as flies, mate and feed while laying eggs. Eggs hatch to larvae which tunnel into the fruit creating tracks in the flesh and distort fruit. Larvae are quite small, but the damage is severe. Cover sprays with an insecticide from early July through pre-harvest is necessary for total control. Sanitation (prompt removal and destruction of fallen fruit) combined with sufficient numbers of red ball traps (about the size of a croquet ball covered with Tanglefoot), can successfully manage apple maggot infestations to somewhat acceptable levels. A useful tool when it comes time to diagnose disease and insect problems: http://www.extension.umn.edu/gardeninfo/diagnostics/fruit/apple/index.html Page 6
Autumn 2011 • Advocate
Feature Continued
S
ometimes it is
Urban Apples
(continued from page 1)
Site Selection (continued): Also critical is soil. A pollution free, live, vibrant, loamy, moderately low pH, well drained soil with moderate organic matter is ideal. Unfortunately, not many are blessed with such a soil. First, perform a soil test for toxins. http://soiltest.cfans.umn.edu/
best to remove
and replace an apple tree with a disease resistant flowering crabapple.
Site Preparation A soil test with pH, phosphate, potassium and micro-nutrients is useful. Add and incorporate the recommended amount of essential elements and granular sulfur (acidifier) as recommended with the soil test. The best suggestion to improve poor soil structure is to loosen the soil mechanically and add organic matter. Cultivar and Rootstock Selection There are apple cultivars and rootstocks available for almost all of Minnesota. The University of Minnesota's Ag. Experiment Station's publication “150 Years of Hardy Plants” lists 23 introduced apple cultivars for Minnesota. http://www.maes.umn.edu/components/7564_02.asp Resistant Cultivars 'Freedom', 'Honeycrisp' and 'Liberty' have been reliably hardy and resistant to apple scab at the U of M, Minnesota Landscape Arboretum's Horticultural Research Center. http://www.extension.umn.edu/distribution/horticulture/M1157.html Rootstock Rootstocks are critical for the ability to clone and grow productive apple trees. The most commonly available is M-7a, a semi-dwarf (50% - 70% of standard). M-7a has drawbacks however. Numerous other rootstocks are available from specialty nurseries. Each rootstock has its own degrees of dwarfing, suckering, disease and insect resistance and stability. Bud-9, a roostock developed in Russia is used extensively at the U of M's Minnesota Landscape Arboretum's Horticultural Research Center. It is very hardy, highly precocious and dwarfing (30% - 40% of standard), but needs support.
Honeycrisp. Photo: Dave Hansen
An excellent source of more information on modern rootstocks: Cornell Gardening Resources: Apple Tree Rootstocks http://www.gardening.cornell.edu/factsheets/ecogardening/appleroot.html Planting bare root, container grown or B&B plants is a personal preference and budgetary consideration. Much research has indicated bare root tree planting is most cost effective long term. Continued on page 8 http://www.hort.cornell.edu/uhi/outreach/pdfs/bareroot.pdf
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Autumn 2011 • Advocate
Urban Apples
(continued from page 7)
Selecting and Establishing Apple Trees in the Landscape Part 2 Planting: All trees should be planted with the root flair at or less than ½” below final grade. Stem girdling roots are a concern with all trees, including fruit trees. http://www.extension.umn.edu/distribution/naturalresources/dd7501.html Support. Staking newly planted trees is a good idea for at least one growing season. As always, secure the tree trunk with a non-restricting soft material that allows some movement of the trunk. Depending on the rootstock, you may want to install a permanent support.
C
edars nearby? Eastern red ce-
dar is an alternate host for cedar-apple rust. Its presence can create a difficult apple growing environment.
Pruning and Training. Pruning is the removal of plant parts to achieve a desirable, pre-determined effect. Training is the positioning of branches and securing them until new wood formation can maintain that position. Pruning and Training of fruit trees must go together within the pomology system. The goals of pruning and training are: • Optimal fruit production on 3 to 6 year old wood. • Filling the volume of the tree canopy with fruit bearing wood. • Ability of the branches to support the fruit. • Reducing disease incidence with good air circulation. • Ease in applying insecticides and fungicides with thorough coverage. • Ease of harvest from the ground.
With these parameters in mind some critical concepts of modern pomology are: • Maintain a central leader (with few exceptions). • Develop a loosely conical tree shape. • Allow for light penetration into the canopy. • Maintain major scaffolds with wide branch angles. • Radially and vertically space branches. o Must not have all branches originating from one plane on the trunk. • Allow the tree to produce fruit ASAP. • Keep the vigor moderate throughout the tree. • Discourage vigorous branches high in the tree. • Renew fruiting wood regularly. • Balance fruit load with vigor. Advocate • Autumn 2011
Honeycrisp - loaded with fruit. Proper pruning can prevent breakage of limbs. Photo: Dave Hansen
See pages 5 & 6 for the clip-and-save factsheet.
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About MnSTAC The Minnesota Shade Tree Advisory Committee (MnSTAC) was established in 1974 by a group of concerned citizens to address the health and well being of community forests. MnSTAC is recognized throughout Minnesota and the country for its expertise, advice, coordination and support for community trees. It is an organization of diverse individuals who represent a broad spectrum of treerelated interests. It fosters and supports local community tree programs across the state so healthy community forests are fully integrated into community development, infrastructure, education and management.
MnSTAC Board of Directors President: Katie Himanga Bob Tomlinson Chuck Dryke Tina Markeson Alan Ek Jeffrey Gillman Eric North Glen Hambleton Jim Vaughn Steve Roos Dave Kleinhuizen Larry Westerberg Barb Spears Anne Oldakowski Craig Johnson Gregg Hove James Burkes Steve Nicholson Dave Auchter Kit Richardson Karen Zumach John Ingleman Ron Norenberg James Lemmerman Dave Moehnke Jill Johnson, Ex-officio Ken Holman, Ex-officio Ken Simons
Minnesota DNR Minnesota Dept. of Ag. Minnesota DOT University of Minnesota University of Minnesota University of Minnesota Minnesota Tree Care Advisor MN Society of Arboriculture American Society of Landscape Architects MN Nursery and Landscape Association Society of American Foresters MN Forestry Association MN Assoc. of Soil, Water and Conservation Districts League of MN Cities City of Eagan Cities of Crystal / Robbinsdale Consulting Forester Utility Forester Local Tree Board Member Tree Trust Hutchinson Technology Inc. Citizen at Large, DNR Region 1 Citizen at Large, DNR Region 2 Citizen at Large, DNR Region 3 U.S. Forest Service Minnesota DNR Parliamentarian
Webinar (archived): "Here Today – Gone Today: Mechanized Removal & Processing of Urban Trees" https://umconnect.umn.edu/p78694155/ Webcasts from the Alliance for Community Trees: First and third Thursday of every month: Noon-1:00 pm Get the schedule, sign up to watch, or view archived webcasts at: http://actrees.org/site/resources/webcasts/ Urban Natural Resources Institute: An initiative of the USDA Forest Service Northern Research Station. E-learning Webcasts Archive: www.unri.org/webcasts/ To subscribe: www.unri.org/e-news/ Advocate • Autumn 2011
Calendar and Web Northern Green Expo January 4-6, 2012 http://www.northerngreenexpo.org/ Save the Dates: March 19-21, 2012 50th annual Minnesota Shade Tree Short Course http://www.mnshadetree.com/ February 16, 2012 Rochester Arborist Workshop www.rochesterarboristworkshop.com Click here for a list of events from: USDA Forest Service, Northeastern Area, State and Private Forestry, Urban and Community Forestry.
December 15, 2012 MnSTAC Membership Meeting
This membership meeting is for the purpose of voting on proposed changes to the MnSTAC constitution www.mnstac.org
Upcoming MnSTAC Forums Third Thursday of the Month 10:00 to 11:00 am December 15: Potluck and Forum Forum Speaker: Jeff Gillman, Ph.D
How Trees Die.
http://www.mnstac.org/ Webs of Interest: Great River Greening www.greatrivergreening.org
Tree Board University www.treeboardu.org
International Society of Arboriculture www.isa-arbor.com
Tree Care Advisor Program www.mntca.org
Minnesota Landscape Arboretum www.arboretum.umn.edu
Tree Link www.treelink.org
Minnesota Nursery and Landscape Association www.mnla.biz
Tree Trust www.treetrust.org
Minnesota Society of Arboriculture www.msa-live.org
Urban Forestry & Horticulture Institute: University of Minnesota www.trees.umn.edu
Minnesota Turf and Grounds Foundation www.mtgf.org
Urban Forestry Index, UFIND http://urbanforestryindex.net/
Books: Trees of the Northern United States and Canada, Author: John Laird Farrar. The Road to a Thoughtful Street Tree Master Plan: A practical guide to planning and design. Authors: Ken Simons and Gary Johnson. Download the PDF. DVD available for the Hmong community Conservation, Education DVD: “The Wildlife and Wilderness Exploration Show“ Contact: David N. Bengston, Ph.D., Northern Research Station, USDA Forest Service, 1992 Folwell Ave., St. Paul, MN 55108 USA, EMAIL: dbengston@fs.fed.us Web Sites: EAB University: Learn more about invasive pests and diseases by tuning in to the Emerald Ash Borer University. http://www.emeraldashborer.info/eab_university.cfm Urban Forest Management Plan Toolkit: http://ufmptoolkit.com/ Changing Roles Webinar Series - active and archived http://www.interfacesouth.org/products/changing-roles/webinars MnSTAC Report to the State of Minnesota http://www.mnstac.org/documents/Inv_Spp_thrt_report_2011_FINAL.pdf
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Mystery Tree
Mystery Tree Answer
Minnesota Shade Tree
Folklore tells us that the armament or 3-pronged thorns (triacanthos) were
Advocate
so robust on some specimens that squirrels would not climb the tree!
A quarterly newsletter published by the Minnesota Shade Tree Advisory Committee Managing Editorial Group:
American Civil War and pioneer historians tell stories about how the thorns were used in carding or felting wool, as needles and to pin tattered Confederate uniforms. I hope the name of this tree is no longer eluding you – because it is the ever popular:
Ken Holman, Karl Mueller, Lara Newberger, Jacob Ryg, and Mark Stennes.
sweet locust a.k.a. honey locust - Gleditsia triacanthos. Photos: Dave Hanson
Editor: Dave Hanson Material in this newsletter is not copyrighted. Reproduction for educational purposes is encouraged. Subscriptions are free. Articles, news items, photos and videos are welcome. This publication was produced with the support of the USDA Forest Service, Northeastern Area; State and Private Forestry. Address inquiries to: Minnesota DNR Division of Forestry 500 Lafeyette Road Saint Paul, MN 55155
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Autumn2011 • Advocate