Photo courtesy of Valerie Price
Newsletter Date Volume 18, Issue 2
Inside this issue:
Too Cold for Chlorophyll? pg.1
Your tree is not a cactus: The Importance of watering. - Eric North pg.2
Supercooling of Plant Tissues in Deacclimated Trees and Shrubs pg.3
Japanese Beetles - Jeffery Hahn pg.4
Forest Service Photo Contest pg.4
Education Updates pg.5
Important Program Updates pg.6
TCA Cookbook pg.6
Summer Volunteer Calendar pg. 7
Valerie Price and Jeff Carroll, Managing Editors
http://www.mntca.org
Too Cold for Chlorophyll? What happens if or when winter returns to our Minnesota springtime gardens? Well, pardon my rhetoric…it depends.
cold-hardy parts of a woody plant: soil temperatures of 1519º F can kill fine roots, the roots that take up the majority of water and nutrients for tree health. Soil temperatures of -5 to - 10º F cause the death of woody roots. If the soils were dry and there was no mulch over the root systems, the damage is likely to be even worse.
It began long ago. Trees and shrubs begin the long, slow acclimation period for winter in mid to late August. This acclimation process is triggered by shorter days, which begins the chemical changes that allow plant cells to reliably tolerate temperatures as low as 40º F or colder. Even though the process begins in August, trees and shrubs aren’t fully ready for winter until well into December in the Southeast region of Minnesota.
After a minimum of 40 days, trees and shrubs can potentially begin the deacclimation process, which is now triggered by temperatures. Different plants require different amounts of degree days, those that are provided by daily temperatures greater than the mid-30s, even though it can drop below freezing at night.
As you’ve probably noticed, it doesn’t take many degree days to get elms and lilacs started! They’re among the first to show Frost crack on a stressed littleleaf linden. Winter, the period of rest and occasional dorgrowth – swollen leaf and mancy (of buds) is a normal and survivable flower buds. Maples are a stress for trees and shrubs that are in their cold hardiness bit more subtle, but the flow of their sap is a sign that the range (e.g., zone 4)…as long as they entered the acclima- deacclimation process has started. Once the deacclimation tion period in a healthy state. Trees that enter the acclima- chemical changes begin, winter hardiness slowly disaption period stressed from drought, nutrient deficiencies or pears and plants once hardy to -40º F can be damaged by pH stresses, over-pruning or construction damage are less temperatures likely to fully tolerate winter’s additional stresses. Their of +25º F! energy reserves are so low that they are more likely to suf- It’s kind of fer frost cracks and cankers, needle or bud death, twig die- like taking off back, cambial death, branch death, root death or complete your winter death. long-johns Volunteer Hours Form pg.8
Did you water last autumn? Dry soils get colder than moist soils and the cold penetrates deeper in dry soils. Trees and shrubs that entered the winter anchored in dry soils are much more likely to lose a lot of roots to cold temperatures from the recent winter. Roots are the least
continued on page 2
Photo by: Jack Schmidling Productions 1
Too Cold for Chlorophyll? ... continued before Memorial Day…not a good idea.
stressed (pre-disposed) trees and shrubs die after inciting events. Potential damage from a mid-spring cold-snap
It’s most tender below. Roots are the least cold hardy parts of a woody plant, followed by the cambium of young trees and branches, flower buds and needles, and finally the leaf buds. Since leaf buds are the most cold hardy, they can emerge and unfold fully in the spring, seemingly unscathed, yet only to be let down by the damaged roots and/or cambium. If the roots or the cambium have been severely damaged, those perfect leaves that emerged wilt, scorch, die and fall off. No water, no life. Crystal ball. What can be expected this spring and summer? Certainly root death on those trees and shrubs unlucky enough to have been in dry landscape soils. Dead roots mean less water for the rest of the plant. Cambial death on a trunk of a corktree…most often this leads to trunk decay. Less water upstairs means more twig die-back, frost cankers, frost cracks, needle death and maybe some could be mild, ugly or enough to finally push the stressed flower bud damage. Trees that have leafed-out or are flow- plants over the edge. Potential damage from 2011’s ering could suffer some (or all) loss of the new foliage and droughty autumn is likely to be much more severe, more flowers if temperatures fall down in the mid-20’s (again, damaging to the tree’s entire system. depending on the different species). If the trees are fruit Damage to the roots from the colder than normal soil temtrees, there’s likely to be a smaller harvest for 2012. peratures could be the worst damage so far. Damage from Leaf loss, flower the upcoming summer and autumn is hard to predict, but if loss, stem cankers the drought persists (it’s definitely not over yet) the damage can all result from in 2013 could be very severe. hail storms, yet very few trees and Now, what to do? shrubs ever die *Advocate regular irrigation and mulching (2-4 inches of from hail damage. organic mulch reduces soil moisture evaporation by 30%) Other examples *Have patience. Wait until mid to late summer before of inciting events pruning out dead wood or giving up on a plant. It takes a (sudden, shortlong time to damage them and a long time for them to reterm damage cover. events) include gypsy moth defoliations, late cold-snaps and *Don’t fertilize if root damage is suspected…that only wind storms. Healthy plants can normally tolerate these makes the situation worse. types of damage and recover just fine. Only previously
Your tree is not a cactus: The importance of watering - Eric North Planting trees in your community during Arbor Day can be Watering and tree care an enjoyable and rewarding activity. By planting trees you There are lots of things to consider from pruning to pest are doing something to positively affect your neighborcontrol, but what about watering? It’s easily forgotten that hood’s streets or parks hopefully for generations to come. trees, like all plants, need regular doses of water in order to However, few of us stop to think about that tree after the survive. In order for an environment to support trees there Arbor festivities have continue on withThe our importance needs to beof about 19 inches-Eric of precipitation Yourpassed. Tree isWeNot a Cactus: watering North (rain and daily lives enjoying the shade and scenery provided from snow) per year. Minnesota has a range of precipitation our large, well- established trees. So, now that you have from 18 inches to 32 inches annually. So, if we get enough planted a tree (or two or three) what comes next? rain, why bother watering trees at all? You might be thinking, “I’ve never seen anyone watering the forests”, and you continued on page 3 2
Your tree is not a cactus... continued are probably right, I haven’t seen that either. However city environments differ quite a bit from forest environments. Watering your tree can be an inexpensive and easy way to Street trees are planted in some pretty small spaces, from 2 reduce trees issues. According foot wide to 8 feet wide along most of our city trees. We to the City of St. Paul it costs ask trees to put up with a lot in the city, from people lock- less than $3 to water a newly ing bikes to them to dicing salts from our winter weather. planted tree for a year. ConsidSome of these are difficult to prevent, but we can help trees ering healthy mature trees have deal with the stressful city-life through watering. been shown to reduce both heating and cooling costs for Lack of water is the number one cause of stress and stunted your home, making $3.00 a growth for urban trees. Like you, when trees are stressed very smart investment. For more information on watering they become more susceptible to illness. Stressed trees, like your street trees please visit http://www.stpaul.gov/ the paper birch become an easy target for the bronze birch index.aspx?NID=853 borer (an insect), which can eventually kill the tree.
Supercooling of Plant Tissues in Deacclimated Trees and Shrubs Ice crystals form most readily when there is a “nucleus” present in water. This nucleus is the beginning of the formation of the ice and the more nuclei there are, the faster the ice crystals spread. Ice crystals can in fact become nuclei, so once the freezing starts, it progresses rapidly compared to the time that it took to begin freezing.
newly emerged leaves. *Dehydration of the plant cells. Most plant tissue death is due to intracellular dehydration. Ice forms in the spaces between cells and draws moisture from the interior of the cells. Eventually, if the temperatures stay cold long enough, the cells become dehydrated.
Nuclei can be in the form of cellular bacteria, polysaccharide molecules, or any other “impurity” in a plant cell’s water content. Freezing can also start on the outside of plant parts, especially if the photosynthetic leaf or stem tissues are moist. Ice crystals start in the water coating the leaves and progresses into the leaves or tender stems.
*Moisture on the outside of the leaves or tender stem tissues. The more moisture on the outside, the more likely there will be damage due to dehydration to the interior. Therefore, cold temperatures accompanied by winds are less damaging than when you see leaves covered with frost at the same temperatures or even warmer.
Cells in different plant parts (e.g., leaf tissues, petioles, cambium, xylem) freeze and sustain damage at different temperatures, all below the traditional “freezing” temperature of 32 degrees F. More tender plant parts, for instance young “bedding” plants such as petunias or tomatoes, are killed at temperatures of 25 degrees F, or even a bit warmer. Plants that are native to higher elevations or colder temperatures tolerate cooler temperatures (reliably to -2 degrees C) depending on the plant part...often to -40 degrees F.
*Location of the plant. Interior leaves, trees/shrubs against buildings (especially masonry buildings) can benefit from the warmer, more protected spaces. Outer leaves or tender stems may be damaged while the interior leaves are unscathed. *Ability to supercool. At this time of the year, leaves on trees and shrubs that have emerged have varying abilities to supercool, that is, lower the temperature of water in and between plant cells without actual crystallization and dehydration. With tree leaves, supercooling is possible down to -2 C...reliably (that’s 28 degrees F), sometimes approaching -10 C (14 degrees F).
Whether or not plant tissues are damaged by spring temperatures once the plants have deacclimated (started active growth after the winter rest period) depends on a number of *Buds. Any plant part that is still protected by bud scales factors: is easily able to tolerate cold spring temperatures, far below *Age of the plant tissue. Leaves that are semi-mature are freezing. The buds may end up being disfigured by desicactually pretty tolerant of cool temperatures, compared to cation, but still functional.
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Japanese Beetles - Jeffery Hahn, Asst. Extension Entomologist As seen on Yard and Garden There have been a lot of questions concerning Japanese beetles (JB) as we go into the 2012 growing season. JB has been increasing in numbers over the last four or five years, especially in the Twin Cities area, although JB are also starting to be found more commonly in other areas of the state as well. They can be challenging to control and people will take any steps they can to reduce their numbers in their gardens and yards.
soon as the 3rd or 4th week of June. And speaking of the early spring, people are wondering whether they can still treat JB grubs this spring or whether it is too late. An important factor to first consider is whether your primary goal is to control the grubs, because you are seeing damage in your turf, or the adults because of damage they have done to garden and landscape plants. If your aim is to reduce the adults by controlling the grubs, you can save yourself the effort as this is not effective. The adults are mobile and can easily fly in from areas outside your property.
The first question people ask is how bad are JB going to be this year. There isn't an easy answer to that question and it undoubtedly will vary according to where you live. If JB was abundant last year, there is a good chance they will be common again this sumIf you are finding turf damage mer. However, a factor that can due to JB grubs, and if you have have an impact on JB numbers is had a lot of adults on your propsoil moisture. The eggs and the erty look carefully for this, then young grubs have a harder time the best time to treat for grubs is surviving in dry soil so if dry in July. If you are going to use a conditions exist when JB are laypreventative, such as imidacloing eggs, that can reduce the numbers of adults that are prid (e.g. Merit), then you should be treating your turf seen the following year. Of course, if the turf area is well when you first see the adults flying. About two to three watered, that will make it easier for JB to survive. weeks after the first adults have emerged, JB eggs are hatching. Preventative insecticides are most effective It is difficult to determine what role the winter weather against the first instar larvae but not the older second and had on JB populations. Although the mild temperatures third instar larvae so the timing is critical. favored JB, the lack of snow cover could have been potentially detrimental to them. The early spring we have If JB grubs are not treated then, it is still possible to conbeen experiencing should not have any effect on JB num- trol them with a curative insecticide, such as trichlorfon bers. However, expect them to emerge earlier than nor- (e.g. Dylox). You can effectively treat JB with a curative mal. In a typical season, JB emerge around the 4th of insecticide until about mid-August. By spring, the grubs July. If the weather holds, the adults could be active as are too large to effectively treat them.
Forest Service kicks off My Neighborhood Forest photo contest. Contest to highlight colors of the urban forest WASHINGTON, April 10, 2012 -- The U.S. Forest Service today announced its My Neighborhood Forest photo contest, celebrating America’s urban and community forests.
www.Challenge.gov for more details on the prizes and contest rules. With 80 percent of the nation's population in urban areas, there are strong environmental, social, and economic cases to be made for the conservation of green spaces to guide growth and revitalize city centers and older suburbs. Urban forests, through planned connections of green spaces, form the green infrastructure system on which communities depend. This natural life support system sustains clean air and water, biodiversity, habitat, nesting and travel corridors for wildlife, and connects people to nature.
The Grand Prize winner will receive $200 in outdoor gear courtesy of the National Forest Foundation. The contest, which runs from April 11 – July 22, seeks to highlight the natural beauty that spring and summer bring to U.S. neighborhoods, communities and cities, as well as the crucial role of trees in the places we call home. Those interested in competing should visit 4
Education Updates Inventory Emphasis Volunteers will be needed to help with inventories in Dakota County, St. Paul, Mora, Bemidji, Brainerd, Mankato and Royalton. This training will not only teach you how to conduct tree surveys but you will also be able to lead the inventory groups. These inventories are vital to communities and with budget constraints they are relying on volunteers to aid them. Tree inventories help to discover what the diversity a community has and allows them to create better urban forestry plans. How can you plant for diversity when you don’t know what you have? Planning for diversity will help them to avoid major losses due to pests and disease.
TCAs Receive Discount on Tree Inspector Program TCAs receive a 50% off discount on May 24ths Minnesota Tree Inspector training and certification testing. This means you only pay $42.50 for the materials, training and exam! This discount is currently only for TCAs coming in as a new Tree Inspector and is not for those renewing their certification.
The training covers: *The value of tree surveys or in inventories and how they are conducted. *A brief overview of common trees and how to I.D. them. *How to correctly measure D.B.H and canopy spread. *How to Condition Rate trees. *How to complete data forms. We will be holding the Tree Inventory Emphasis Training on May 5th from 10:30-5:30 with an hour break for lunch. The training will cost $25 if you bring your own lunch and $35 if you want lunch provided. To register go to http://www.mntca.org/emphasis-training-registration/
The workshop you attend includes basic instruction so that you can demonstrate the following qualifications: be able to identify all native tree species, with or without leaves, and all felled or downed trees with bark intact common to your work area; know and understand the biology of Minnesota's most common shade tree pests; be familiar with symptoms of oak wilt and Dutch elm disease, and be able to identify other problems affecting oaks and elms; know the proper method of collecting samples for disease diagnosis; know the approved control methods for these common tree pests; be familiar with recommended tree species used in replanting programs, their planting requirements, and the care of these trees after planting.
The certified tree inspector program was implemented in 1974 in response to Dutch elm disease and oak wilt. Since then, hundreds of communities have participated and there are more than 800 certified tree inspectors in Minnesota. Certified tree inspectors have passed a test in which they demonstrate proficiency in Emerald Ash Borer, Dutch elm disease and oak wilt management, tree identification, firewood identification, and shade To register go to www.mntca.org/tree-inspector/ tree management. Tree inspectors must attend annual print out the form and send to the address on the form. recertification workshops to learn the latest information on tree care, exotic species management, shade tree management, tree selection, insect and disease identification, tree health care and other timely topics. Those who volunteer for Fruits of the City as a Neighborhood Coordinator receive free classes from them. For more information or to register go to http://www.mnproject.org/food-FruitEducation.html
Fruits of the City: Renewal Opportunity
There are some opportunities to get in some Renewal Education hours through the non-profit Fruits of the City. Fruits of the City aims to capture fresh fruit that would otherwise go to waste and redistributes it to those in need. If you attend these sessions as part of your Renewal please fill out the Renewal Opportunities form on www.mntca.org Soil Basics for Thriving Orchards and Gardens will count for 1 hour of the Plant Selection requirement. April 24th Fruit Pests and Diseases will count for 1 hour of the Plant Soil Basics for Thriving Orchards and Gardens – Fred RoHealth Issues Requirement. zumalski 5
Location: Bachman’s on Lyndale 6:30 – 8:00 P.M. Cost: $20 http://www.eventbrite.com/event/soilbasics Description: Soils are the first critical component of a successful orchard or garden. It's a deep subject, but understanding the basics of soil nutrition, aeration, drainage and the soil food web can go a long way in setting up for sucess. This 'how to' course will have you walking away with exact steps for conditioning and maintaining healthy soil. Bio: Fred Rozumalski is an ecologist and landscape architect currently employed in the water resources division of Barr Engineering Company in Minneapolis, MN. A believer in the power of every land owner's potential to help regenerate ecological balance, Fred has developed a specialty in designing practical landscapes that sequester carbon, harvest stormwater, and conserve energy. His work ranges from writing city-wide green infrastructure plans, to restoring native ecosystems, to designing corporate urban environments that feature perennial food crops. Fred is committed to teaching others to implement sustainable landscapes.
May 8th Fruit Pests and Diseases – Jeffrey Johnson Location: Greater Frogtown Community Development Corporation 6:30 – 8:00 P.M. Cost: $10 http://www.eventbrite.com/event/fruitpests Description: Come learn how to control the most serious and damaging pests on your fruit trees and shrubs. This class will cover basics of pest control on Apples, Pears, Apricots, Raspberries, Blueberries, Grapes, Strawberries and Currants. Bio: Jeffrey Johnson is a Landscape Gardener with the Minnesota Landscape Arboretum, University of Minnesota. He is a woody plants specialist maintaining the trees and shrubs collections throughout the public cultivated areas in the Arboretum's 1125 acres. Jeffrey has been a professional horticulturist for 30 years. At the Arboretum he has managed the HRC's orchards, Landscape Plants Breeding Program nurseries, recruited and retained a substantial volunteer corps, taught adult education classes, given tours and cultivated donors.
Important Program Updates you have volunteered this year. So instead of looking for your name, look for your number. Hopefully this will fix the issue of folks not remembering which hours they’ve already turned in
Membership Cards Sent along with this newsletter is a membership card, which you will see has a membership number on it. Hold onto this card! I will be sending out information about what Volunteer hours you have submitted and what Renewal hours you have completed. This number will be your identifier so that I’m not telling everyone how much
Try it out on the Volunteer Hours and Renewal Hours Tracker that I sent with the newsletter. Let me know what you think!
TCA Cookbook Available The Tree Care Advisor Cookbook, "Growing and Eating Fruits from Trees and Shrubs in Minnesota", that was put together by several TCAs and pulled together and edited by Rebecca Koetter is now available for purchase! Get a sneak peak at www.mntca.org/tca-cookbook/
pickup by sending a check to: TCA 115 Green Hall 1530 Cleveland Ave. N St. Paul, MN, 55108 If you would like one please send a check written out to the University of Minnesota and write TCA in the memo, for $33 if you want to have one reserved for you to pick up at a later date, or if you would like one mailed to you please send a check of $37.90 and one will be send to you as soon as it is received. This information is also available on the TCA website, just look in the menu bar (no pun intended).
The book gives the growing requirements and recipes for every fruit including common fruits such as apples all the way to gooseberries. This book makes for a great reference and helps you make some great food! Get one today! There are 100 pages in total and they cost $32.40 to print, put in spiral binding. They also have a clear plastic cover which is great in case of spills. We are charging $33 for them. It will cost $4.90 if you would like it shipped to you or you can reserve one for
If you have any questions about the cookbooks please feel free to e-mail info@mntca.org 6
Summer Volunteer Calendar If any of these events interest you, go to the http://www.mntca.org/volunteer-opportunities/calendar/ The TCA Volunteer Calendar has great descriptions of events and contact information for those running the events. Great River Greening - Restoration Event Saturday April 21, 8:30am – 12:30pm Indian Mounds Regional Park, St. Paul, MN Minneapolis Park and Recreation Earth Day Watershed Clean Up Saturday, April 21, 9:30am – 12:00pm Multiple Minneapoils Locations, see description TCA - DirT Meeting Wednesday, April 25, 6:30pm – 8:30pm 116 Green Hall, 1530 Cleveland Ave. N, St. Paul, MN, 55108 City of Plymouth - Bare Root Tree and Shrub Sale Friday April 27, 12pm – 5pm Plymouth Maintenance Facility City of Plymouth - Bare Root Tree and Shrub Sale Saturday, April 28, 7:30am – 1:00pm Plymouth Maintenance Facility City of St. Paul - Arbor Day Fruit Tree Event Saturday, April 28, 9am – 12pm Horton Park, St. Paul, MN
Tree Trust - Minneapolis Tree Distribution Saturday, May 12, 2012 City of Minneapolis Impound Lot - 51 Colfax Avenue North, Minneapolis Great River Greening - Restoration Event Saturday, May 12, 8:30am – 12:30pm Cherokee Bluffs Regional Park, St. Paul, MN University of Minnesota- Rochester Study Planting Saturday, May 12, 8:30am – 12:30pm or 8:30am-4:30pm Essex Park, Rochester, MN Tree Trust ReForest St. Louis Park Community Planting Saturday, May 12, 9am – 12pm Oak Hill Park 3201 Rhode Island Avenue South, St. Louis Park, 55426 Tree Trust- Minneapolis Tree Distribution Sunday, May 13, 2012 City of Minneapolis Impound Lot - 51 Colfax Avenue North, Minneapolis
Tree Trust - St. Louis Park Tree Distribution Saturday, May 5, 7:30am – 12:00pm 2231 Edgewood Avenue South, St. Louis Park, 55426
Tree Trust - Minneapolis Tree Distribution Monday, May 14, 2:45pm – 7:15pm City of Minneapolis Impound Lot - 51 Colfax Avenue North
Oakdale Tree Planting Saturday, May 5, 8am – 12pm Castle Elementary, 6675 50th St. N., Oakdale, MN, 55128
Great River Greening - Tree Planting Saturday, May 19, 8:30am – 12:30pm Rum River Easement Property, Cambridge, MN
Great River Greening - Invasive Removal Saturday, May 5, 8:30am – 12:30pm Pilot Knob, Medota Heights, MN Tree Trust - St. Louis Park Tree Distribution Saturday, May 5, 7:30am – 12:00pm 2231 Edgewood Avenue South, St. Louis Park, 55426 Oakdale Tree Planting Saturday, May 5, 8am – 12pm Castle Elementary, 6675 50th St. N., Oakdale, MN, 55128
City of Lake Elmo and MNDot - Lake Elmo Planting Saturday, June 2, 8:45am – 1:00pm 3800 Laverne Avenue N., Lake Elmo, MN, 55042 City of Lake Elmo and MNDot - Lake Elmo Planting Saturday, June 2, 8:45am – 1:00pm 3800 Laverne Avenue N., Lake Elmo, MN, 55042 Fruits of the City - Apple Bagging Saturday, June 23, 2012 Details are to be determined. Check the website for updates.
Great River Greening - Invasive Removal Saturday, May 5, 8:30am – 12:30pm Pilot Knob, Medota Heights, MN 7
Tree Care Advisor Volunteer Hours Current Contact Information (please fill out entirely unless you prefer to turn your hours in on the web) Name: Address: City, State, Zip Code: Email Address:
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Tree Care Advisors 115 Green Hall 1530 Cleveland Avenue North Saint Paul, MN 55108-6112 8