VOL. 7, NO. 1
COMMUNITY FOREST PROFILE
Great River Greening
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By Emily Barbeau
here is an organization in the Twin Cities committed to making our green infrastructure more aesthetically pleasing and ecologically sound. While many people may have heard about Great River Greening, they might not know what makes this organization so interesting. It is time to learn what makes this nonprofit so unique, why it is crucial to our urban forest, and where you can see their work throughout the Twin Cities. An architect’s vision for the Mississippi Riverfront was first presented to St. Paul community leaders in 1992. The vision was to create the “Great River Park”. The Saint Paul Foundation provided the seed money, and the three initial goals for the project continue today in various forms: restore ecological function to the Mississippi River valley, create attractive green space on the river near downtown St. Paul, and involve citizens in planting efforts. Greening the Great River Park project got off the ground in 1995. The project’s first event brought out 175 volunteers to plant trees and shrubs near the Harriet Island entrance. By the end of 1995, about 700 volunteers had planted 2,591 trees and shrubs. At this point, Greening had only two full time staff members, a consultant and a few seasonal employees. It’s amazing how this organization mobilized so many volunteers and accomplished so much in one year! Their success was due to Greening’s unique perspective on volunteers. “Volunteers are our purpose,” notes Deborah Karasov, Executive Director, Great River Greening. “They are our purpose, not the means to an end.” In other words, volunteer involvement is just as important as the planting and restoration work. Greening’s volunteer events are designed to be fun, family-friendly events where people can experience the natural world in an urban location, where people can learn about planting, restoration, and some of the skills to apply that knowledge to their own yards. Volunteers are broken up into groups, and lead through activities by a volunteer supervisor. There are about 150 active volunteer supervisors at Greening, who attend training on topics such as how Greening strives to run an event and how to correctly plant a tree. The supervisors, some of which are Great River Greening continued on p. 2
Inside THIS ISSUE 2 Perspectives Column 4 Forest Health: Understanding Primary and Secondary Tree Feeding Insects 6 Dispel-A-Myth: Nothing can be Done to Help Trees Adjust to Various Stresses that Come With Tough Planting Sites 8 Clip & Save: The American Elm: A Place in the Past—A Place in the Future 14 Tips for Building a Relationship with Your Legislator 15 STAC Info and Calendar
Visit MnSTAC on the Web at www.mnstac.org
The Minnesota Shade Tree Advisory Committee’s mission is to advance Minnesota’s commitment to the health, care and future of all community forests. ADVOCATE • Winter 2005
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PERSPECTIVES COLUMN
Answering Tree Questions by Phone is Rewarding for Both Advisor and Caller By Cliff Johnson
For more information about the Minnesota Tree Care Advisor Program, check their web site at www.mntca.org
I field hundreds of phone calls each year from Carver and Scott County residents. My specialty is trees. It seems like I haven’t had a question in several years that hasn’t been a repeat from previous years. Questions are predictable by season. Springtime triggers questions on slow-leafing trees. April frosts generally cause phone calls weeks or months later about trees that failed to leaf out properly. Spring also spurs winter burn questions on evergreens. Late spring prompts calls about sawfly larvae on spruce, split trunks on maples, rodent damage to stems, anthracnose and spruce fungal diseases. Summer, fall and winter also spark predictable, seasonal questions. If you are uncertain how best to answer phone questions, or haven’t volunteered for live phone duty because you fear you won’t have the right answer, here’s a tip: Consider a typical visit to your family doctor. In many cases when you visit a general practitioner about a health problem, the doctor doesn’t know ahead of time what problem brought you to the clinic. You may describe a condition on your head, your foot, or somewhere in-between. Your problem could be internal or external. Regardless, what process does your doctor follows to diagnose your condition? Of course: carefully selected questions. “Tell me where it hurts.” “How long has it been hurting?” “When did you first notice the problem?” Your conversation with a garden caller should follow the same process. Chances are, the caller won’t give you all the facts you need to identify the problem. You will often need to probe deeper to uncover facts that will allow you to make an accurate diagnosis. If the caller says his pine tree is losing needles, clarify first which species of pine you are dealing with -- or that it is, in fact, a pine. I play golf with people who call every tree with needles pine trees, regardless of whether they are firs, spruces or cedars or pines. Ask how long the trees have been in the ground, how they were planted (containerized, balled and burlaped, by hand or by machine), how often they are watered, the fertilization history, wind exposure, and when the problem was first observed. Too many callers want a magic potion to fix every problem. It has been my experience that the cause for at least half of problem calls is improper planting and plant stress. This has been especially true during the late summer of 2004. Dozens of homeowners called about their maples. What is the cause of the leaves turning red in early August, and dropping leaves in mid-summer instead of October, when it’s normal? The answer, in most cases, is stress. The University of Minnesota calls it “maple decline” -- a whole combination of factors that weaken maples and make them susceptible to secondary invaders. I continue to answer phone questions about tree problems because it is interesting for me and because it provides a much-appreciated service to tree owners. People have strong feelings of concern, affection and attachment for their trees. They are seeking accurate, unbiased answers that they can trust. Every once in a while, I still get a call about a problem that is unfamiliar. It is then that I tell the caller, “Hey, that’s a new one. I’ll have to research that and get back to you.” Then I check one of the University of Minnesota horticulture sites, or do a Google search, find the answer, and follow up with the caller by phone or email. If you haven’t done phone duty for tree calls, I encourage you to give it a try. It’s a great way to help others and to stay abreast of what’s happening in our urban forests. Cliff Johnson is a Minnesota Tree Care Advisor.
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already Tree Care Advisors and Master Gardeners, are also offered advanced training classes throughout the year to refresh and expand their knowledge. These are great incentives for people to make a real commitment to the organization. It’s no surprise that many of the volunteers are long term, coming back for several events a year. In 1999, as the Great River Park project was reaching the end of its 5-year timeline, Great River Greening reanalyzed the organization’s role in the community. Should they end with the project, or was there a community need for their organization? Greening’s goal was to build capacity within communities, to be a catalyst for planting and restoration by offering technical expertise, and workshops to guide private landowners and public agencies. Luckily, they decided there was a role for Greening in our community. In 1999, the Great River Park project became a new nonprofit, with programs including the Big Rivers Partnership, the River Steward program, and the fee-for service Greening Strategies. Incidentally, by this time, more than 8,000 volunteers had planted 31,000 trees and shrubs in the river valley. In 2000, Great River Greening began to involve volunteers in restoration activities like exotic species removal and prairie seed collection. Anyone who has done a round of buckthorn removal would wonder how Greening draws volunteers to do hard and sometimes tedious work like buckthorn removal and collecting prairie seeds. Apparently, they do so by looking at each type of volunteer experience in a different light. The planting projects bring volunteers back several times throughout a year throughout the region, while the restoration volunteer is more inclined to participate in one event near their home, and then apply the knowledge to their own yard or pass it on to community members. This is a key part of Greening’s goal for capacity building, because activating and educating citizens will allow them to take on roles like park stewards in their communities. The West Side Bluff project is one of the most interesting and ambitious projects that Great River Greening has undertaken. It is an area with stunning views of the Mississippi River Valley. They have a ten-year involvement agreement with the community to restore the eroded and disturbed areas, as well as the oak forest dry prairie remnants. Greening has collaborated with the Bluff Task Force of the West Side Citizens Organization, and the City of Saint Paul Parks and Recreation Division. The two main goals for the restoration project are to improve the ecological health of the
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GREAT RIVER GREENING
Great River Greening from p. 1
Volunteers plant grasses on the West Side Bluff in St. Paul. bluff vegetation and also to allow for viewing areas of the river. In contrast, the Brooklyn Park project was fairly short-term. The city wanted a natural experience for their park users along the river. The area was once a farm field but after teaming up with the National Park Service, Greening designed a woodland and prairie area, rain-gardens for storm water infiltration, and a demonstration garden so that park users could apply some of the knowledge to their own back yards. The corridor created has reduced erosion and storm water run-off, and has created better wildlife habitat. To launch and promote the new river park, the partnering organizations held a planting event in May 2004. Our urban forest is more ecologically sound and aesthetically pleasing thanks to the work of Great River Greening. They have had the ability to analyze their role in the community and evolve since their 1992 inception, utilizing their resources to best build capacity for planting and restoration work . You can see their work up and down the Mississippi River Valley, from Belle Plain to Hastings, and in the coming years you’ll see their involvement in the Greater Twin Cities along the Minnesota and St. Croix River Valleys. Emily Barbeau is the Assistant Forester with the City of Minnetonka.
For more information on Great River Greening, visit their web site at www.greatrivergreening.org
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Planting projects bring volunteers back several times a year, and then they apply the knowledge to their own yards or pass it on to community members.
FOREST HEALTH
Understanding Primary and Secondary Tree Feeding Insects By Steven Katovich The white pine weevil is another common Those who deal with insects that attack trees Minnesota insect that should be defined as a prioften refer to specific pests as either primary or mary pest despite not killing its host tree. Adult secondary species. Unfortunately, that terminolfemale weevils seek out and select young white ogy can mean different things to different people. pine trees, with large diameter terminals, for Because of this, it becomes important to make egg-laying. In other words, they select the fastest some clear distinctions when using these terms. growing trees in a stand. Larval survival is high in One of these distinctions is that referring to a “healthy” young white pine where they kill only tree feeding insect as a primary or secondary spethe terminal portion of an infested cies should only be done with those tree. insects that attack and feed within There are, of course, primary 1) the cambium layer and adjacent Primary insect species that do kill their host tree and phloem and xylem; and 2) growing species that these are some of our most signifitips and roots of a tree. Leaf feeding cant forest pests. One example would insects and sapsucking insects should kill their host be the emerald ash borer. This Asian not be referred to as primary or sectree are some beetle can infest and complete develondary species. opment in healthy North American The text book definition of a of our most ash trees. Tree death follows, though “primary” insect species is one able significant it may be 2-3 years after the initial to attack a healthy, living tree and forest pests. attacks. One interesting point with complete its normal development this example is that emerald ash therein. A “secondary” insect species One example borer may not be a primary pest of would be incapable of attacking and is the emerald ash in its native Asian range. Some completing normal development in a insects can change from primary to healthy tree. This implies that secondash borer. secondary status based upon the tree ary insects can complete development species they are infesting. Our native only in unhealthy trees. ash species appear to have no inherent ability to Notice that there is no mention made of any defend themselves against emerald ash borer, and requirement for these insects to kill trees. In other this allows the insect to act as a primary species in words, to be classified as a primary insect does North America. Asian ash species however, apparnot require the ability to kill a host tree; it simply ently have evolved defenses against this phloem means that an insect can complete its life cycle in borer. So, in its native range, emerald ash borer a healthy tree. would act more as a secondary pest, capable of There are several relatively common “prideveloping in an Asian ash, but only within trees mary” insects that would not be considered tree weakened by drought or some other cause. killers. One example in Minnesota is the sugar Bronze birch borer, Agrilus anxius, a commaple borer, one of our native long-horned mon species here in Minnesota, changes from beetles. This sun-loving beetle selects sugar maple secondary to primary based upon the tree species trees for egg laying that are open-grown or growit is attacking. When attacking our native paper ing along woodlot edges. These trees can be very birch, the bronze birch borer would be considered healthy individuals. Sugar maple borer larvae tunsecondary because it cannot complete developnel in the phloem and then into the sapwood, and ment in healthy paper birch trees. However, when eventually, adult beetles emerge. Tunneling damit encounters one of the white-barked European age can be significant, but since this insect is not birches planted in a yard in Minnesota, it can act gregarious, most attacked trees survive.
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S. KATOVICH
event that weakens many trees. We do have many secondary pests that persist by attacking dying branches and trees that are struggling to survive. Many of these never become tree killers. When observed, their role as a secondary species should be recognized. They Emerald ash borer. This exotic insect is may indicate that acting as a primary species on ash. a tree has other significant health problems that are providing opportunities for these secondary insects to persist. In conclusion, anyone using the terms secondary and primary should set some boundaries on the definition they are applying. This is necessary because technically, primary insects do not need to be involved with killing trees, a common misconception. Further, some insects can shift from secondary to primary status depending upon the tree species they are selecting and the population levels that they reach. Finally, these same terms are often applied to pathogens, especially root infecting fungi. For those, the definition of primary and secondary may be different. Steven Katovich is a Forest Insect Ecologist with the USDA Forest Service.
For more information on forest health, visit the USDA Forest Service, St. Paul Field Office web site www.na.fs.fed.us/spfo/index.htm
S. KATOVICH
as a primary species. Even though a European birch tree may be growing under optimal conditions and would be regarded as very healthy, it has no ability to defend itself against the birch borer. This allows bronze birch borer to shift to a primary species, but only when attacking European white-barked birches. Further, in some situations, insects can change from secondary to primary status by increasing their population size. This works when large numbers of insects mass attack a tree, overcoming the ability of even a healthy tree to defend itself. Some of our bark beetles species are classic examples of this process, including one called the spruce bark beetle. This species can reach very high population levels following storm events that knock down many spruce trees, thus providing abundant breeding material. Once high population levels are reached, spruce beetles can shift to a primary species. Large numbers of beetles attack and overwhelm even a very healthy trees’ ability to defend itself. This works for bark beetles because of their ability to congregate and attack trees in mass. Many secondary species cannot shift to a primary species but still become, on occasion, significant pests. This occurs when large numbers of host trees are weakened or stressed during some event, such as a drought or an outbreak of a leaffeeding caterpillar. Drought and leaf loss weakens trees and allows secondary insects an opportunity to successfully complete development in trees they normally could not infest. Once trees recover their health, secondary pest outbreaks tend to quickly subside. Bronze birch borer outbreaks in paper birch and two-lined chestnut borer outbreaks in oak stands are two classic examples here in Minnesota of secondary pests that do not shift to a primary species, yet kill many Bronze birch borer adult and D-shaped trees. They do exit holes. This native beetle can shift this when birch or from a primary to a secondary species oak forests under- depending upon the species of birch it go some stressful attacks.
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Bronze borer and two-lined chestnut borer are two classic examples of secondary pests that kill many trees.
DISPEL-A-MYTH
NOTHING CAN be done to HELP TREES ADJUST TO various stresses that come with TOUGH PLANTING SITES. by Scott Robinson What is so tough about tough planting sites?
A 7 foot by 7 foot planting area, 2 feet deep, is the minimum space needed for trees that naturally stay small
Tough planting sites can be planting islands in parking lots, roadsides and medians, sidewalk treegates, narrow boulevards and plaza plantings. They are often characterized by limited space above and below ground for tree growth and unsuitable soils for plant health. These are the main factors that inhibit tree growth. In addition, mix the intense heat reflected off hard surfaces with the likelihood of toxic de-icing build-up in the soil as well as salt coating unopened buds, and you pretty well have a recipe for failure. What can be done then, to lessen the effect of some of these factors? Could you get trees established in tough planting sites, and once established, end up with beautiful trees that justify the extra costs incurred with extensive planting bed preparation? Providing adequate space for root growth could enable trees to better tolerate heat from hard surfaces by increasing their moisture gathering capacity. According to J. Urban, long term tree growth requires a minimum 100 cubic feet of soil available for root growth. Urban also states that a depth of two feet is adequate depth and that additional volume is best achieved by increasing the surface area. Thus, a 7 foot by 7 foot planting area, 2 feet deep, is the minimum space needed for tree growth for trees that naturally stay small. Urban also suggests that connecting individual planting spaces into linear planting beds allows even greater area for roots to grow into and increase their capacity to gather water and nutrients. Soil can be modified or replaced altogether by special mixes designed to correct problems associated with construction. Since roads and hard surfaces require compacting the soil for structural stability, areas within and adjacent to them tend to be poorly drained and dense. Furthermore, mechanical soil compaction can mix up the natural soil horizon, placing what nutrients the soil did have at the surface, out of the reach of plants. It is commonly believed that there is limited benefit to replacing the existing soil surrounding the planting site with a quality topsoil. First, imported topsoil can be deficient in nutrients, have pH problems, be poorly drained etc. Secondly, potential interface (where the old and new layers meet) problems can be created
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between the existing soils and the added topsoil, mainly impeding water flow between the two layers and making the transition difficult for growing roots. Recipe for Success But what if you combined quality topsoil with additives to correct for nutrient, pH, and drainage deficiencies? And what if you followed the minimum soil volume requirements for root growth and replaced that amount of soil in the planting site? Could adequately mixing the existing soil and the added topsoil mix to create a 6 inch transition zone reduce the interface problems? This example is a possible recipe for a welldrained site. The soil mixture is concentrated in the top 18 inches of the soil where it is available for the roots and can do them the most good. Here, then is a possible soil recipe for a welldrained site. We will call it: Select Topsoil Borrow Select Topsoil Borrow can be formed by starting with a good garden center quality of topsoil that has been screened and pulverized with the following additions: •
Iron Sulfate spread over existing topsoil at a rate of 2 lbs per 100 Sq. Ft. and incorporated uniformly to a 6 inch depth by a spading machine. Iron Sulfate lowers the pH in the existing soil in anticipation of future root growth in this zone.
This is followed by: •
Spreading commercial slow release fertilizer, analysis 22-5-10, added at a rate of 1 lb per 1000 Sq. Ft. The 22-5-10 ratio mimics the amount and type of nutrients plants are able to absorb naturally. Slow release allows nitrogen to be present in the soil for longer periods of time.
This is followed by: •
Spreading garden center quality topsoil, added at a rate 18 inches thick, followed by spreading sphagnum type peat moss, added at a rate of 2 inches thick and blended by spadWinter 2005 • ADVOCATE
ing machine to a total depth of 12 inches. The peat moss adds organic matter to the soil that will help it hold water for longer periods of time. The peat moss also lowers the pH of the soil. A cross-section detail, describing the installation of this recipe is shown below in Figure 1. Plant selection appropriate to the site conditions could also contribute to successful planting in tough sites. Tolerance of de-icing salts, excessive heat and cold, and adaptability to a wide variety of soil types add to the chances of trees in tough sites according to a publication on tree and shrub selection in tough sites by the University of Minnesota Extension Service. So there are actually quite a few things that can be done in tough planting sites to enable trees to have a longer life expectancy and significantly greater cost effectiveness over the long run.
REFERENCES Urban, J. 1990. Evaluation of Tree Planting Practices in the Urban Landscape. Proceeding from the Fourth Urban Forestry Conference. Phillip Rodell, Editor. Johnson, Zins and Shippee. Tough Trees and Shrubs for Tough Sites. University of Minnesota Extension Service. www.extension.umn.edu/distribution/naturalresources/DD7502.html Minnesota Department of Transportation. Standard Specifications for Construction 2000 Addition. www.dot.state.mn.us/tecsup/spec/
Scott Robinson is a Landscape Designer with the Minnesota Department of Transportation.
Figure 1
Planting Detail for a Well Drained Site Along a Roadway, Sidewalk, Parking Lot or Plaza
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The American Elm:
A Place in the Past—A Place in the Future
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by Chad P. Giblin and Jeffrey H. Gillman
fter several years of relative quiet, we are faced with a terrible Dutch elm disease (DED) outbreak. We have all seen the newspaper articles, evening news reports and witnessed the red and orange “marks of death” banding American elms throughout the southern half of our state. For many of us, this was the summer for DED. Many experts are quick to point out that sanitation has been lax for several years, causing an enormous increase in elm bark beetle populations which vector the disease. Others suspect the fungus itself (Ophiostoma ulmi) may have changed somehow, perhaps becoming more aggressive. In the circumstances that we currently find ourselves, there are a few issues that need to be addressed. First, we must understand why we have lost so many trees to DED this season. Second, we should figure out what can we do to lessen the severity of future disease outbreaks. And finally, we need to take a look at our replacement options. To answer the first two questions, we decided to interview some local experts on urban forest management and Dutch elm disease. Here’s what we found.
Dutch Elm Disease 2004—What Happened? Jim Hermann—Forester, Minneapolis Park & Recreation Board
American Elm
Jim Hermann helps manage one of the biggest populations of urban elms in Minnesota, and has been dealing with the threat of DED since the early days. This year, though, things just didn’t happen like previous years. When he noticed the amount of disease by the first part of June, Hermann suspected “this was going to be an unusual year!” Since then, the Minneapolis Park & Recreation Board (MPRB) forestry crews have been working overtime to deal with DED management and removals. In the city of Minneapolis, elm losses this year stand at 9,910 trees. This puts 2004 as the third highest loss of American elms since 1963 when DED was first discovered in the city. In 1977, the city had its highest losses with over 30,000 elms removed. 1978 ranked second with over 20,000 elms lost. Interestingly enough, this year’s losses were split down the middle between public and private trees with 49.74% lost on public land and 49.36% lost on private property. In 1977 and 1978, the public private ratio was roughly 2:1. In the interim years, total annual losses rarely went over 3,000 elms, and remained low enough to not to draw too much attention. Since the onset of the outbreak this year, the MPRB has been doing everything possible to reduce the number of trees lost. Their first order of business was to bring on five additional tree inspectors, bringing the total up to fifteen for the city. They also brought in two additional bucket trucks and extra chippers to help with the inspection and removal process. Hermann expects the crews will be working well into December and January to remove just the dead and diseased elms. During a normal year, they would have wrapped up DED removals by mid-October, with plenty of time for a small fall planting and continued sectional trimming. From the beginning, Minneapolis crews have put the emphasis on sanitation. The sheer volume of removals has put pressure on MPRB to carefully manage their wood waste. In prior years, whole logs were hauled out of the city limits to various recycling sites. This year, however, they brought in a tub grinder to process diseased logs in selected staging areas in the city. Keeping the wood waste in town allowed them to process diseased logs much more quickly and efficiently. This saved time, labor, and potential disease/insect transmission involved in hauling the logs long distances off-site. Minneapolis is anticipating
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similar disease pressure next year and is already planning for it. Hermann is very involved in trying out the resistant elm varieties. His interest helped establish a cooperative research project between the MPRB and the University of Minnesota to evaluate the various elms available in the trade. Since 1999, researchers have evaluated over 550 elms of 17 different varieties for use in the MPRB system. They found some winners and a few losers. “The big thing is that they serve a real purpose…the elm is a tough tree,” says Hermann, “We’ll just fine tune the selection and incorporate the good ones into our planting plan.” Finally, moderation is best in all things. Hermann states that the MPRB is taking a cautious approach to replanting large numbers of any particular tree. We only need to look at Chicago’s ban on planting more ash trees as their response to the nearby emerald ash borer infestation in Michigan. Minneapolis has approximately 19% ash trees on the streets and is trying to limit the over-planting of any one particular species or variety. With the potential risks involving ash and the emerald ash borer (EAB), Asian long-horned beetle (ALB) and Sudden Oak Death (SOD), the MPRB wants to keep as high a tree diversity as possible. In addition, Hermann stresses the need for a good tree inventory, which would serve as a survey tool, allowing for quicker, more efficient planning and response to exotic pest introductions or disease outbreaks.
Mark Stennes—Plant Pathologist/Consulting Arborist, Top Notch Treecare Stennes is insistent on his “three inspections a year” regimen.
Mark Stennes has been on the front lines in the battle against Dutch elm disease for at least 30 years. He has field experience backed by the inquisitive nature of a true plant pathologist and this compels him to be a true advocate for the American elm. Stennes is very concerned about the long-term health of elms in our urban forests, and agrees with Hermann that next year will be just as bad, or worse than this year for DED. Stennes thinks we should have seen this year coming. He believes that reduced emphasis on sanitation and removals for the last 3 to 4 years may be to blame. He also suspects that money earmarked for the scouts and tree inspectors is often the first to be cut when the municipal budget needs trimming. This leads into the paradox stating: “you can’t remove it if you can’t find it!” Stennes states simply that if we have better scouting, we can have faster removal and less DED. Stennes supports his inspection and sanitation program with his 25 years of experience (19762000) in managing Dutch elm disease on the Minnesota State Fairgrounds. Stennes is insistent on his “three inspections a year” regimen. The first inspection should take place by the middle of June to check for undetected DED carry-over infections from the previous year. A second inspection by the end of July is used to confirm any suspicions generated in June. The third inspection should happen around the end of August or early September, which can allow for detection of current year infections and create a window for pruning and early therapeutic fungicide treatment, increasing the chances of success dramatically. Following each inspection, any trees that cannot be saved must be removed promptly. “Ruling with an iron fist is critical in this regard.” Stennes thinks that we can save about four out of five insect inoculated trees from DED if we follow this system, and dramatically reduce the incidence of new infection. In terms of preventative or curative chemical control, Stennes supports the use of injections for homeowners wishing to treat elms on private property. With the exception of select, highprofile trees, the public institutions and municipalities just cannot afford preventive injections. Instead, they should focus on time-tested and economically proven cultural management techniques. Stennes is an American elm purist. He feels that many of the hybrid elms are less than spectacular in form and function and often have problems with elm leaf beetle. Stennes is currently spearheading the work to produce and evaluate the “St. Croix elm” (see below) and is looking forward to the possibility of having one more resistant U. americana to work with.
The Biology of Pathology This year’s infection levels have generated a lot of discussion about a change or mutation in the DED fungus. Many people think this might explain why the disease was able to infect apparently healthy trees so quickly. To help answer some of these questions, we interviewed Jason Smith, a Ph.D. student working in the Forest Pathology Lab at the University of Minnesota. We were very interested to see if there has been any recent work done in his lab to examine the genetics and biology of the DED fungus.
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Jason Smith—Ph.D. Student, University of Minnesota First off, Jason Smith reports that there is no official project or funding that is currently looking at the genetics of the fungal population. He also firmly states that there is no new evidence to indicate that the fungus is any different this year than before. He does admit, however, that there could be new strains developing. Smith also points out that, this year especially, many people have been confusing fungal virulence with a possible increase in fungal aggressiveness. A fungal pathogen is either virulent (able to infect a host) or avirulent (unable to infect a host). If a new strain of the fungus is discovered that is able to move faster through the tree, that would indicate an increase in aggressiveness, the virulence should have remained the same. Also, there “…doesn’t need to be an increase in aggressiveness, there could just be an increase in incidence.” This would imply that the insect vector may have changed, perhaps feeding on the tree in greater numbers and increasing infection potential. Smith stressed that anytime there is a major change in a disease epidemic, the three components of “The Disease Triangle” should be examined: the host, the environment, and the pathogen. First, we know that the host really hasn’t changed. In terms of the environment, the last two summers, both 2002 and 2003, have been particularly dry and potentially stressful on the trees. Many sources say stressed trees can’t defend against pathogens as well as healthy trees, but this is still largely speculative in the case of DED. Smith suggests that the most effective plan would be to examine the pathogen population first, and if there is no change there, then the vector population should be examined. There are a number of different dynamics with the American (Hylurgopinus rufipes) and the European (Scolytus multistriatus) elm bark beetles. The American elm evolved with the American elm bark beetle, whereas the European bark beetle is an introduced pest. Finally, there is the “wild card” Chevy beetle (S. schevyrewi) which was found in Fridley, Minnesota this year. The role this insect has to play in DED is still unknown. USDA sources suggest that it may be even more aggressive and breed in larger numbers than the European bark beetle; for Minnesota these claims are still speculative. Like Jim Hermann, Jason Smith is a big supporter of field evaluations for DED resistant elms. He mentions that much of the screening that disease resistant varieties undergo occurs in a very controlled environment. Once they reach the nursery or landscape setting they undergo a number of stresses that can’t be replicated in a research setting. He does state, however, that most elms are quite adaptable and that both the newer resistant hybrids and the resistant true U. americana selections should be tolerant of most of the environmental problems that the original elms faced. Smith really stresses the need to replant with American elms, but takes it one step further by stating that we really need to keep “a wide diversity as possible” in replanting and replacing trees. He also goes on to state that “…we don’t always have to plant only the slow-growing, long-lived, most disease-resistant…trees” as long as you are planting appropriately for the site you should have a good chance for success. If you limit your palette to trees fitting only the characteristics just mentioned,, you’re bound to miss out on a number of good selections. There are always potential threats for just about any tree you plant. Everyone is aware of the emerald ash borer threat and even the potential devastation of the ubiquitous Norway maple by the Asian long-horned beetle. Still, this hasn’t stopped planting of those trees. Smith’s bottom line is that we must be as vigilant as possible in protecting the remaining elms we have and still keep an open mind about what we choose to replace them with.
“…we don’t always have to plant only the slow-growing, long-lived, most diseaseresistant…trees”
Some Resistant Elm Options Now that we know a little more about where we are in terms of control of the disease, we need to look to the future. What are some options for filling those voids left by mature elm removal? Many growers and foresters are becoming hesitant to plant Norway maples (due to the aforementioned ALB issues and possibly invasiveness) and ash (due to the EAB threat). Here’s a list of the elm varieties we’ve tried here at the University of Minnesota and what we think of them:
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Accolade™ U. japonica x wilsoniana This Morton Arboretum introduction has been a great option for a disease resistant elm for many years. This tree has a mature form that is very similar to the American elm, but it is slightly more upright and generally has smaller leaves. Accolade™ has shown excellent performance in winter hardiness tests in the Twin Cities area and generally outperforms many other varieties in terms of insect resistance as well. Just this year, we discovered two Accolade™ elms that had DED. One was on the University of Minnesota St. Paul Campus and one was in the city of Minneapolis. This is the first time, that I am aware of, that Accolade™ has been reported to have the disease. While this is disconcerting, it is a good reminder of what the term resistant means. None of these selections are or should be considered “DED proof”. They could all, theoretically, get the disease. It should just occur at a much lower rate than on elms that are considered susceptible to this disease.
Triumph™ U. japonica x wilsoniana
Triumph™ is another new selection out of the Morton Arboretum in Illinois. Its parentage includes Vanguard™ and Accolade™. If you are looking for a tree with larger leaves than Accolade™, this might be the one for you. It has been relatively carefree in the nursery setting and has all the qualities of the Accolade™ and Cathedral without many of the drawbacks like branch inclusion, breakage and so forth. So far, this is one of our favorites. This selection has also shown excellent performance on brownfield sites. Several have been on Nicollet Island for four years now and seem to have great promise for tough sites!
None of these selections are or should be considered “DED proof”. They could all, theoretically, get the disease.
Homestead U. (a complex hybrid with U. pumila, U. carpinifolia, and U. hollandica heritage)
Homestead is another decent tree that we have had for only a couple years. While its leaves are smaller and the form isn’t at all like an American elm, it still proved quite tough and vigorous at the nursery. Homestead is very similar to Siberian elm (U. pumila) in form and leaf characteristics. It did suffer some sunscald and cambial damage the winter of 20002001 in our nursery evaluations, but it didn’t appear to be adversely affected by it. This tree is fairly easy to find in the trade. Townsend and Douglass report that, in their research, 10% of Homestead clones died the second year after DED inoculation. There have been a few, unconfirmed reports of DED on these trees in the trade, but these reports have been rare.
Patriot U. wilsoniana x ʻUrbanʼ This is another newer selection out of the U.S. National Arboretum. Patriot has outstanding summer foliage that is quite glossy and very dark green. Its form generally has been upright in our evaluations, but photos of more mature trees show it to have a form very similar to that of U. americana. This tree is somewhat hard to find in the trade, but numbers have been increasing in the last couple of years. In the same study by Townsend and Douglass (mentioned above), Patriot showed 100% survival 7 years after DED inoculation. This tree is definitely in our “Top 5” list.
Danada Charm™ U. japonica x wilsoniana Another Morton Arboretum introduction, Danada Charm™ ranks number one in our evaluations in annual percent caliper increase and number two in stem growth rate. It is literally the fastest growing elm in the nursery! Its leaves are larger than those seen in Vanguard™, Accolade™, and Patriot and still lustrous and fairly dark green. On the downside, this tree is also the number one tree in our evaluations to develop stem breakage due to narrow crotch angles and included bark. We have had occasions where a large specimen lost a good portion of the crown due to breakage during high winds or a thunderstorm. This is a great tree, it just requires a little more maintenance than some of the others.
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Vanguard™ U. (complex hybrid with U. japonica and U. pumila heritage)
Vanguard™ is another Morton Arboretum selection that is extremely vigorous. This tree follows closely behind Danada Charm™ in annual growth rate. It has a fairly upright form in the nursery and the leaves are similar to American elm in size and color. While this is a tough tree and grows very quickly, it also has some problems with poor branch architecture. Of the 17 varieties evaluated in our nursery, it was second only after Danada Charm™ in incidence of broken branches due to bark inclusions. This tree has also had some problems with foliar leaf diseases in the spring. These usually don’t cause any long-term problems, but may create problems with aesthetics early in the season.
REFERENCES
Commendation™ U. (complex hybrid with U. carpinifolia, U. pumila, and Accolade heritage)
Anonymous. 2004. Scolytus schevyrewi –A bark beetle new to the United States. http://www.fs.fed. us/r2/fhm/reports/ pest_update_sschevyrewi.pdf
Another Morton Arboretum selection, Commendation™ has been very vigorous in our nursery evaluations. It is reported to have excellent drought resistance and adaptability to tough sites. The ultimate form on this tree is more oval than vase-shaped but is still quite attractive. In our evaluations Commendation™ ranked #3 in both percent annual caliper increase and annual twig growth. This tree should be a good all-around tree for a variety of sites in the urban forest.
Discovery U. japonica
Like Accolade™, the Discovery elm has been around awhile and many people are already familiar with its characteristics. It is slower growing than some of the other varieties, but still packs on stem caliper at a good rate. Some sources suggest its ultimate form may be vase-like but, in our experience, it is fairly upright. This tree has excellent resistance to foliage feeding insects and appears to be quite hardy in St. Paul, Minnesota. There are a number of these already growing in the Minneapolis Parks system; I am not surprised when I hear reports that they require above-average pruning schedules. This tree has a very dense crown.
Dunn, Christopher P. (ed.). 2000. The Elms: Breeding, Conservation, and Disease Management. Kluwer Academic Publishers. Boston. MA.
Cathedral U. pumila x japonica
Cathedral is another long-time favorite DED resistant selection out of the University of Wisconsin. Due to its vase-like form in the nursery, this variety was selected by the University of Minnesota to replace American elms lost on the Northrop Mall on the Minneapolis Campus. This selection requires a lot of attention in the nursery, ranking #4 in number of breaks due to inclusion in our evaluations. As it calipers up, a little less maintenance is required, but attention is still required to avoid co-dominant leaders and removal of excessively large temporary branches.
Santamour, F.S., Jr. and S.E. Bentz. 1995. Updated checklist of elm (Ulmus) Cultivars for use in North America. Journal of Arboriculture 21(3). International Society of Arboriculture, Champaign, IL.
Valley Forge U. americana
We tried out quite a few Valley Forge from the U.S. National Arboretum. This tree has a lot of well-earned notoriety for being hard to manage in the nursery! Once it gets out of the 2 to 3” caliper range it seems to “settle down” a little and takes on a more manageable form and habit. If you are interested in trying this tree, I would recommend it only if you are able to devote enough time to pruning it for long-term health and branch structure. It is reported to be 96% resistant to DED in inoculation studies and should be fairly hardy to our Zone 4 region.
Princeton U. americana
Dziuk, P.M. 2004. Exotic bark beetle…found here, there and everywhere? Plant Protection Review 2(3). Minnesota Department of Agriculture, St. Paul, MN.
Like Valley Forge, this is another true American elm. Princeton is one of the oldest American elm selections available. It was actually selected for “superior horticultural qualities” prior to the DED epidemic. This tree is slightly more upright than many of the seedling American elms around. We have had a little trouble with winter injury and tip dieback in this selection. Outside of the nursery setting, this seems to be less of a problem. Perhaps with a little less fertility and more ground cover, this tree will prove to be hardy in Minnesota.
Camperdown U. glabra
We were excited to try this variety because of its unique form and character. Apparently, the parent tree in Dundee, Scotland creates a “living room” under its weeping crown and is quite popular with visitors. This tree is the only true Wych elm or Scots elm (U. glabra) evaluated in our nursery. The first year after planting in fall of 1999, the Camperdown performed quite well, but once we slipped into almost “normal” winter temperatures, we saw severe winter kill and dieback. Ninety percent of these trees were lost in the winter of 2002– 2003 and those that survived are
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in very poor shape. There are some specimens planted in Como Park in St. Paul that are doing quite well. In the park, they might have the benefit of a unique microclimate or a protective ground cover that was lacking in the nursery setting.
Frontier U. carpinifolia x parvifolia
Frontier has some of the most spectacular deep burgundy-red fall color I have ever seen. Its big drawback for Minnesota is poor winter hardiness. In the nursery setting, we have seen severe twig dieback almost every winter. The tree usually “bounces back” but it lacks the form and integrity that we find in truly hardy selections. We are currently evaluating some trees on their “own roots”, to see if this may improve winter hardiness. Until then, this is one selection we are not recommending for Minnesota.
REFERENCES Stennes, Mark. 2003. Good news for the American elm. Minnesota Shade Tree Advocate 5(4). Minnesota Shade Tree Advisory Committee, St. Paul, MN.
New Horizon U. pumila x japonica
The New Horizon elm is a product of a cross between U. pumila and U. japonica and is another introduction from the University of Wisconsin. It has many of the features that we are looking for in a tough tree for the urban forest: fast growth, good insect resistance, and good DED resistance. We found that co-dominant leaders and heavy side-branches can develop fast on this variety, so be sure to keep an eye on the leader for the first few years.
Pioneer U. glabra x carpinifolia
Initially, we took a chance on Pioneer. Sold as a USDA Hardiness Zone 5 tree, many folks may pass it over on that account. Do give it a try, though, it has proven to be quite hardy for the last 5 winters here in St. Paul. Pioneer’s form is quite different from the American elms but it is very easy to train as a young tree. We ran a growth regulator study two years ago, where we didn’t prune a block of different elms for two full growing seasons. At the end, Pioneer was one of the very few with an acceptable form – all without any pruning!
Townsend, A.M. and L.W. Douglass. 2004. Evaluation of elm clones for tolerance to Dutch Elm Disease. Journal of Arboriculture (30)3. International Society of Arboriculture, Champaign, IL.
Prospector U. wilsoniana Prospector is a straight Wilson elm (U. wilsoniana) selection and has similar hardiness issues that we saw in Frontier. It performs OK during the growing season but clearly lacks the hardiness of the other selections. This tree also has some problems with stem breakage due to bark inclusion. Like Cathedral and Valley Forge, it requires a lot of attention to establish good branch structure and a central leader at a young age. We are continuing our evaluation of this tree with plants from a new source.
The “St. Croix” American Elm U. americana You may remember reading about this tree in the Fall 2003 issue of the Minnesota Shade Tree Advocate. This tree has shown great promise for being DED resistant. The University of Minnesota is currently working in cooperation with Mark Stennes to secure funding to study propagation of this tree and hopefully produce enough clones to establish a DED inoculation study in the field.
The Future Next year we plan on taking an “American-only” approach to our elm evaluations. Currently, we have gathered a large amount of data relating to the hybrids and feel quite confident in making recommendations about their performance for nursery growers and urban foresters in the Upper Midwest. Unfortunately, the true American elm selections aren’t as available in the trade as their hybrid counterparts and haven’t undergone the intense scrutiny the others have. With a little persistence we hope to find as many selections as possible and really put them through the wringer!
Chad P. Giblin is a Research Scientist and Jeffrey H. Gillman is an Associate Professor at the University of Minnesota, Department of Horticultural Science.
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Keep up with the latest research at the University of Minnesota, Department of Horticultureʼs Teaching, Research, and Extension (TRE) Nursery by visiting www.tre.umn.edu
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Tips for Building a Relationship with Your Legislator By Janette K. Monear
W
hy bother creating a relationship with your legislator? Good question – but a better question is, why not bother? If the old adage “the squeaky wheel gets the grease” is true, then we better show up, speak up and help create the environment that enhances our jobs, supports our communities and promotes trees. We better “speak for the trees” because it not only affects what we are doing right now, but it affects the future of our children and creates a better quality of life for everyone. Advocacy, it’s the right thing to do. So, as an advocate how do you go about creating a relationship with your legislator? • Do a little background research about the person that you would like to have help you. Look at their environmental scorecard. The Minnesota League of Conservation Voters provides a yearly report about how each legislator votes on specific environmental issues. (www.mnlcv.org). This will give you an indication on how environmentally friendly they are and will provide you with some insight into their level of interest/knowledge for your cause. Remember that decision makers are human beings and they have their personal and professional agenda’s. Try to put your issue in the context of the legislator’s own district and how it will affect their constituents. • Be committed to spending some time providing them with information that will help them articulate the importance of your cause. Focus on the information that is scientifically credible, supports your cause and provides them the most information with the least amount of verbiage. Never embellish your story. Give them a short written executive summary of your request with web site references that staff can use to locate additional information. • Respect and cultivate a relationship with his/her staff. They can make your access to the decision maker easy or hard, and normally they are doing the research and work needed to expand the request or to act upon it. • Invite your legislator to visit your program at least annually, keep them updated if there are changes and make sure that you provide a media opportunity like an Arbor Day event for them to attend so that they can be seen and heard supporting your cause. Send a short note when they have done something that you think has made your community and/or state a better place to live and remember, help during their election campaign. • Schedule a 15-minute face-to-face meeting with them. Dress respectfully, be punctual, start your meeting with a compliment, be friendly and polite and thank the legislator for taking time to meet with you. Introduce yourself as a constituent and if you are representing a specific group, let them know the name of the group. Assume support, state your purpose and ask for a specific commitment or action that you would like them to take. Allow them to respond, listen carefully to their advice and don’t interrupt. And, make sure never to criticize another legislator, lobbyist or the opposition. Don’t burn bridges……. • Don’t be afraid to “speak for the trees”. Show your passion and believe in your cause. Have your case prepared and remember to answer the following questions: Why is this issue important? How does is affect their constituents and communities? What do you want them to do? Be specific and to the point! • Write a thank-you note (after meeting with them), and summarize any action items from the meeting and let them know that you plan to stay in touch. Franklin Delano Roosevelt said, “Those that show up make the rules”. So, let’s start showing up and help make the rules! Showing up in person is always the most effective but other opportunities could include a telephone call, writing a letter—not a postcard, and the least effective tool—e-mail. However you decide to advocate, remember, you are making a difference. Advocacy is about self-empowerment— the most effective kind of force that can change the course of action. You can and will make a difference! Janette K. Monear is the Director of Urban & Community Forestry, Tree Trust
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STAC INFO & NEWS
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 tree-related 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: Ken Simons—763/717-9366 Vice President: Michael Max, EnvironMentor Systems, Inc. —763/753-5505 Valerie Cervenka, Minnesota Department of Agriculture— 651/296-0591 Jim Hermann, Mpls Park & Rec Board/Forestry—612/370-4900 Ken Holman, DNR/Forestry—651/296-9110 Steve Nicholson, Kunde Company—651/484-0114 Gary R. Johnson, U of M/Forest Resources—612/625-3765 Robert Slater, MN Dept. of Transportation —507/529-6145 Kirk Brown, Tree Trust—651/644-5800
Regional MnSTAC Committees Southeast STAC Chair: Henry Sorensen—651/388-3625 or 651/385-3674 Sec./Treas.: Katie Himanga, Heartwood Forestry, Lake City—651/345-4976
Headwaters-Agassiz STAC (HASTAC) Chair: John Johnson, City Forester, City of Thief River Falls—218/681-1835 Sec./Treas.: Jeff Edmonds, DNR Forestry, Bemidji—218/755-2891
West Central STAC Chair: Bob Fogel, Director of Parks, City of Moorhead—218/299-5340 Sec./Treas.: Dave Johnson, DNR Forestry, Detroit Lakes—218/847-1596
Northeast STAC Chair: Kelly Morris, City Forester, City of Grand Rapids—218/326-7481 Secretary/Treasurer/Technical Advisor: Dan Jordan, IRRRA Mineland Reclamation —218/254-7967
Calendar
URBAN AND COMMUNITY FORESTRY
Events
January 19-21, 2005, Mid-Am Horticultural Trade Show, Chicago, Illinois, www.midam.org January 23-25, 2005 North Dakota Nursery Convention/Trade Show, Fargo, North Dakota, Contact 701886-7673 February 15-16, 2005 Minnesota Society of American Foresters, Mankato, Minnesota, Contact Greg Russell 320-231-5164 or greg. russell@dnr.state.mn.us February 15-17, 2005 North Dakota Urban and Community Forestry Association, 18th Annual Tree Care Workshop, Fargo, North Dakota. Phone 701-461-8496 February 18, 2005, Rochester Urban Forestry Workshop, Rochester, Minnesota Contact Jay Maier 507-286-8733 March 15-16, 2005 Iowa Shade Tree Short Course, Iowa State University, Ames, Iowa, www.ucs. iastate.edu
Deforesting the Earth: From Prehistory to Global Crisis. Michael Williams. 2002. University of Chicago Press Manual of Cultivated Conifers. P. Den Ouden. 2002. Kluwer Academic Publishers
Web Sites Forest and Shade Tree Pathology www.forestpathology.org Healthy Forests Initiative www.healthyforests.gov Human Dimensions of Urban Forestry and Urban Greening www.cfr.washington.edu/ research.envmind/index.html Minnesota DNR Buckthorn Site www.dnr.state.mn.us/invasives/ terrestrialplants/woody/buckthorn/index.html National Plants Database http://plants.usda.gov/
March 22-23, 2005 Minnesota Shade Tree Short Course, Saint Paul, Minnesota
National Urban and Community Forestry Advisory Council http://treelink.org/nucfac/
April 18-20, 2005, Trees & Utilities National Conference, Omaha, Nebraska, www.arborday.org
Product Labels and MSDS www.cdms.net/manuf/
May 23-25, 2005, Urban Wildlife Management National Conference, Omaha, Nebraska, www.arborday.org August 6-10, 2005, International Society of Arboriculture’s Annual Conference, Nashville, Tennessee, www.isa-arbor.com
New Publications Canada’s Forests: A History. Ken Drushka. 2003. McGill-Queens University Press. Communication and Public Participation in Environmental Decision Making. Stephen P. Depoe, John W. Delicath, and Marie-France Aepli Elsenbeer. 2004. State University of New York Press. Community Forestry in the United States. Mark Baker. 2003. Island Press
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Decision Methods for Forest Resource Management. Joseph Buongiorno. 2003. Academic Press
Tree Biology Dictionary www.treedictionary.com/ DICT2003/index.html Tree Ordinance Guidelines www.isa-arbor.com/publications/ordinance.asp Urban Forestry Benefits and Costs www.urbanforestrysouth.org/ pubs/ufmanual/benefits/ Wisconsin DNR Emerald Ash Borer Site www.dnr.state.wi.us/org/land/ Forestry/FH/Ash/index.html Woody Plant Seed Manual www.wpsm.net
For handy up-to-date links to web sites of interest, be sure to visit www.mnstac.org
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Minnesota Shade Tree Advocate A quarterly newsletter published by the Minnesota Shade Tree Advisory Committee. Managing Editorial Group: MnSTAC Education Committee (Gary R. Johnson, Lara Newberger, Mark Stennes, Jeff Rick, Ken Holman, Patrick Weicherding, James Burks and Emily Barbeau) Editor-in-Chief: Judy Slater judyslater@earthlink.net Design: Creative Services Unit, MNDNR 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 U.S.D.A. Forest Service, Northeastern Area; State and Private Forestry. Address inquiries to:
-- Galeain ip - Altiem MacDunelmor DEBORAH ROSE, MNDNR
Judy Slater Minnesota Shade Tree Advocate 115 Green Hall 1530 Cleveland Ave. N. St. Paul, MN 55108 Printed on recycled paper using soy-based inks.
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