2003 Issues

VOL. 5, NO. 1

Winter 2003 COMMUNITY FOREST PROFILE

Hendricks, MN

by Janette Monear, Tree Trust

itting on Lake Hendricks, a 1,634-acre recreational lake, is the City of Hendricks.

Hendricks is located on the Minnesota–South Dakota border about 35 miles west of Marshall, near the Midwest Center for Wind Energy. More than 200 wind towers dot the landscape with their rotating arms signaling that you are within a few miles of Hendricks. The open prairie, ag land, wind and lake that surround Hendricks give you the feeling of being one with the land. Hendricks has a population of about 684 and although this doesn’t sound like a large number of people, the community represents what most of us nostalgically refer to as a small “home town” community. You will find the Mayor, along with some of the business owners, senior citizens and local farmers chatting and eating lunch in the local diner, City Hall busy with people dropping off payments and asking the clerk about her day, and the playground of the school noisy with the laughter of small children.

Hendricks has a 9-hole golf course, campgrounds that accommodate more than 26 campsites, a city park, and the Lincoln County Pioneer Museum. The downtown looks like something that Grant Wood would paint and the enthusiasm behind the city is its people. They organize annual celebrations such as the Syttende Mai (Norwegian Holiday), Summerfest and the Buffalo Ridge Two-Cylinder Club tractor show. And they contemplate the future of Hendricks. They are not unlike other small rural communities; their concerns for economic development and environmental integrity are important to them. In an effort to plan for the future and to stimulate some new ideas around these two topics, the City of Hendricks, in September of 2001, requested a visit from the Minnesota Design Team.

Hendricks continued on p. 3

The Minnesota Shade Tree Advisory Committee’s mission is to advance Minnesota’s commitment to the health, care and future of all community forests.

COURTESY CITY OF HENDRICKS

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Dawn Dubats (left) and Kirsten Andenas of Tree Trust trained volunteers on planting day in Hendricks. ◆◆◆

Mn ReLeaf Grant Preapplications Due ◆ See page 16 for more information

Inside This Issue 2 President’s Corner 4 Dispel-A-Myth: DiseaseFree Crabapples 7 Clip & Save: Problems With Over-Mulching 10 Buckthorn Busting 13 Forest Tent Caterpillar and Your Trees 15 STAC Info 15 Calendar

Visit MnSTAC on the Web at www.mnstac.org

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PRESIDENT’S CORNER

New MnStac Programs

by Lorrie Stromme Earn Free CEU’s When You Attend MnSTAC Meetings When you attend a MnSTAC meeting, you can receive one free ISA-approved continuing education unit (CEU).

Each MnSTAC meeting runs two hours. The first half of the meeting is reserved for the information exchange. During this time, government agencies and professional arborists discuss the latest field reports and research news. One CEU is granted for the second half of the meeting, which features a speaker and a program. In August, no formal MnSTAC meeting is scheduled. Instead, we offer a field tour . . . and 2 to 2.5 free CEU’s. That’s 12 free CEU’s each year, just by attending MnSTAC programs. If you’d like information about upcoming MnSTAC meetings and programs, please contact Lorrie Stromme at 612-788-5157 or stro0293@umn.edu.

Watering and mulching help buffer the shock of transplant. Newly planted spruce and crabapple line the roadside in the background.

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Keep Up with Trees and MnSTAC . . . via the Tree News E-mail Newsletter Keep up with news releases, recent publications, upcoming workshops, grant opportunities, and helpful web sites by reading MnSTAC’s monthly E-newsletter. The E-News is available on MnSTAC’s web site www.mnstac.org, or you can sign up, through the web site, to receive the E-News by email. When you visit MnSTAC’s web site, don’t forget to check the tree tips, community resources, calendar of events, and the agenda for the next MnSTAC meeting.

MnSTAC Sends Speakers to Minnesota Planners Conference In September 2002, Don Willeke, Janette Monear, Ken Holman, and Mark Schnobrich gave well-received presentations at the annual conference of the Minnesota Chapter of the American Planners Association. Topics that were discussed by MnSTAC speakers include the environmental and economic benefits of trees, tools to incorporate trees into comprehensive plans, developing landscape ordinances, and a case study of how the City of Hutchinson developed a tree program. Contact MnSTAC if you would like to invite a speaker to your meeting.

New Editor MnSTAC welcomes Judy Slater as the new editor for the Minnesota Shade Tree Advocate newsletter. Ms. Slater has a Master of Arts degree in writing, and she is a member of various professional writers’ organizations. You can contact our new editor at JudySlater@earthlink.net. She looks forward to hearing from you.

Urban forestry holds within it the opportunity to help communities realize a vision for the future while still holding on to the past.

Lorrie Stromme, the President of MnSTAC, works for the City of Minneapolis as a policy aide. She is pursuing a master’s degree in horticulture.

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Winter 2003 • ADVOCATE

Hendricks, from p. 1 The Minnesota Design Team, formerly known at the Governor’s Design Team, is a group of dedicated professional volunteers whose passion and commitment are around sustainable community development. Since 1983 the Minnesota Design Team has visited more than 80 communities, working to develop a shared vision for the future. When the team’s 12 to 20 experts come into a community, The trail then returns from the park to City Hall. they listen to as many people as Like the trail, the history, culture, environment possible, so that all views and and economic possibilities are woven together. hopes for the future can manifest in Creating a design for all of the open space areas is the vision that will be presented at the first plan of action. This will enable the comthe end of the weekend. Weaving munity and its existing partners to identify various the community’s input into design opportunities for funding and other partnerships concepts, drawings, and explanatoto help manifest a dream into reality. ry notes, the Design Team leaves Maybe the work through community forestry behind a collective vision on will spark more efforts—efforts that could create a poster-size drawings that interpret 30-mile bike trail that traverses the countryside the community’s shared vision. This vision then spurring more opportunities for local B & B’s, or helps the community to start to identify and put the creation of a downtown art center that will together a plan of action that will help retain their help to make Hendricks a wonderful destination. existing community character and historic roots Urban forestry holds within it the opportunity but moves them towards renewal—both economic to help communities realize a vision for the future while still holding on to the past. and environmental.

Contact the Minnesota It enfolds within it the opportuniIt was after the MDT visit that Design Team at: ty to create who you want to be Minnesota Project, Tree Trust and www.minesotadesignteam.org without leaving behind who you the MDT got together to examine are. And, it manifests the best of how we could help communities what is possible. Urban forestry isn’t just about implement some of their new ideas and manifest trees, it’s about people. People working together their energy and enthusiasm into realistic plans. for the future.

With an OEA grant, we were able to work with the City of Hendricks and together we have plantJanette Monear is Tree Trust’s Director of Outreach Programs. ed more than 136 trees and shrubs, and hundreds of flowers, with the help of the Minnesota Dept. of Transportation’s Partnership program. Working with the community, Tree Trust has also been able to identify how urban forestry can be integrated to create more economic stability.

A hard-working community task force has identified several open space planting opportunities and has looked at connecting them with a circular trail that starts at the City Hall information center and continues past the school, hospital and one of four Lutheran churches to a potential 12 acre arboretum site, then meanders down main street, past an area for the sculpture garden, on to the history center and into Lake Hendricks park.

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Volunteers mulch newly planted flowers 4” deep, trees and shrubs 6” deep. Over 55 volunteers from the Hendricks community worked planting trees and perennial flowers. ◆◆◆

PHOTOS COURTESY OF CITY OF HENDRICKS

Hendricks Beautification Commitee members volunteered long hours on all aspects of the partnership. Even so, they happily finished up the job of hauling 95 cubic yards of woodchip mulch. ◆◆◆

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DISPEL-A-MYTH

Those Irresistible Crabapples

By Janna Beckerman Extension Plant Pathologist, Yard and Garden Clinic

“A good name, like good will, is got by many actions and lost by one.” —Lord Jeffery

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JODY FETZER, MINNESOTA LANDSCAPE ARBORETUM

Figure 1. Though apple scab does not normally kill a tree, it’s a devastating disease that lowers the tree’s resistance to other problems. ◆◆◆

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rnamental crabapples are to the Midwest what flowering dogwood is to the East and crape myrtle is to the South. The springtime beauty of flowering crabapples is unrivaled, and in a good spring, blossoms cover every branch in bold displays of pink, red or white flowers. The diversity of flower color is only surpassed by the many varieties of structural shapes available to choose from: columnar, pillar, weeping, spreading. Size is also negotiable, with cultivars as small as 6 feet and as large as 25 feet. Because these plants are actually apple trees (yes, the fruit is edible!), they produce fruits in a wide array of colors (yellow, orange and red), sizes and edibility. ( Just because you can eat them doesn’t mean that they all taste good!)

So, when I was asked if I “might be interested in writing an article for the newsletter on the topic of “Disease-Resistant Crabapples Won’t Get Diseases,” I was bummed. You see, I can’t. I’d be lying: Disease-resistant crabapples do get disease.

And some of these diseases can be fatal to the tree. How can that be?

The term “disease resistance” evokes a common misperception that the plant is able to completely fight off disease. Many people believe that this resistance is conferred against all diseases.

This is incorrect. Disease resistance is limited to specific diseases, although a given plant may have multiple resistances. The letters ‘VFN’ on a pack-

Winter 2003 • ADVOCATE

THE PLANT DISEASE CLINIC, UNIVERSITY OF MINNESOTA

age of tomato seeds denotes resistance to the diseases Verticillium wilt, Fusarium wilt and root knot nematode.

In understanding what resistance is, it is important to remember that a resistant plant can still be infected by a given pathogen. However, the resistant plant is less likely to become seriously infected than a “susceptible” counterpart. Why? You ask. What makes one plant resistant and not another? Some factors that contribute to resistance include thicker leaf cuticle (the waxy outer coating of the leaf), smaller stomates (gas exchange pores), and the ability to make enzymes that destroy toxins needed by pathogens to infect.

Resistance isn’t the only trait that breeders seek to incorporate into new cultivars. In some instances, true resistance to a given disease is not available, but the ability to tolerate a disease is.

Tolerance, unlike resistance, is the ability to withstand infection, even at high degrees, and still yield or not be killed.

Unfortunately, most people confuse resistance with immunity. Immunity is described as the inability of a pathogen to cause disease. For example, it is impossible for an ash tree to get Rhizosphaera needlecast of spruce. The ash is said to be immune to the disease.

Crabapples, like most plants, are immune to most diseases. As such, crabapple will never become infected with citrus canker, wheat leaf rust, or soybean sudden death syndrome. Crabapple is commonly infected with many diseases, including fire blight, cedar-apple rust and scab.

In Minnesota, one of the most serious diseases affecting crabapples is scab.

Figure 2. Symptoms of apple scab first appear as diffuse, olive to dark gray, velvety lesions on leaves and fruit. ◆◆◆

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Pity the homeowner who has a tree that is susceptible to apple scab. In August, just when that homeowner desperately is wishing for shade, their tree, their pride and glory of May, is completely defoliated (Fig. 1). They are raking up spotted leaves and moldy fruit in August and hating every minute of it. The homeowner talks to his neighbor across the street, who also has a crabapple. Her crabapple also looks gorgeous in spring, but keeps its leaves until a proper time in autumn. Even its fruit “behaves,” and stays on the tree, looking like brilliant red ornaments, all winter long. Unable to stand it any longer, he asks her about her crabapple. She replies that it’s called “Christmas Holly,” and no, she never sprays it. Convinced, our homeowner goes out and purchases three of the same plant and puts them in his yard.

Fast-forward ten years. His little trees have grown to be about 10 feet tall. Our homeowner is still grilling applewood-smoked bratwurst in his backyard, in between all the thunderstorms. It is an unbelievably wet year, one of the wettest on record. And then, he sees it: The spots!

Apple scab, caused by the fungus Venturia inaequalis, affects apples, crabapples and pears. It is quite possibly the most common disease of crabapples in the Midwest. Symptoms first appear as diffuse, olive to dark gray, velvety lesions on leaves and fruit (Fig. 2). Fruit lesions begin developing brown, corky scabs. Infected leaves eventually turn yellow and fall off the tree. Severely affected trees can be completely defoliated by late July to early August. Although some homeowners worry that the tree has died due to defoliation, scab does not kill the tree outright. Instead, it slowly weakens the tree over time, and increases the likelihood of infection by opportunistic insects or pathogens.

Scab can be managed through intensive fungicide use, with sprays being applied every 10 to 14 days throughout the growing season to achieve effective control (Fig 3, following page).

For this reason, most homeowners are encouraged to select and plant scab-resistant cultivars. A number of cultivars with high levels of resistance to scab are available. The cultivar in our story, “Christmas Holly,” is described as slightly susceptible to scab. But why did it take ten years before the disease struck?

Crabapples, to p. 6

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Crabapples, from p. 5 JANNA BECKERMAN, UNIVERSITY OF MINNESOTA

Figure 3. Scab can be managed through intensive fungicide use, with sprays being applied every 10 to 14 days throughout the growing season to achieve effective control. These leaves show how incomplete fungicide coverage results in infection, which in turn reduces leaf size and health. ◆◆◆

wetter than average years to build inoculum levels to a degree that makes an epidemic possible. In Minnesota, state climatologists have reported a period of unusually wet weather during the last few years.

“Resistance is Futile.”

—The Borg Queen, Star Trek–The Next Generation

“It’s the constant and determined effort that breaks down resistance, sweeps away all obstacles.” —Claude M. Bristol Regardless of the level of resistance (and remember, we are talking about resistance, not immunity) a cultivar is purported to possess; host, pathogen and environment all interact in creating a disease triangle. Unusually wet weather favors repeated sporulation by the fungus. This translates into the production of millions of spores. All it takes is one spore, a new aggressive spore, that is finally able to achieve what the others could not: an established infection. After that, our aggressive spore invades and reproduces asexually, to create more aggressive spores. Suddenly, we have a population of aggressive spores. This process may have occurred late the previous year, and the few spots produced by the new aggressive strain went unnoticed. However, environmental conditions only encouraged spore production this year and resulted in a “resistant” cultivar falling prey to disease. The genetic makeup of the tree hasn’t changed, but the genetic makeup of the pathogen rapidly evolved to create disease.

Our breakdown of resistance may not have been due to a change in the scab population.

Unusually wet weather translates into an extended growing season. This prevents leaves from maturing, leaving them susceptible to infection.

Other possible factors include heavy application of nitrogen-based fertilizers, which are also known to reduce plant defense response and result in a breakdown of resistance.

On the other hand, years that do not favor the scab pathogen, that are unusually dry, limit spore production and result in plants that may be considered more “resistant” than they actually are. It may also take several normal to slightly

Pathogen

Host Environment

The Disease Triangle

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Let’s face it: You’ve got to die of something.

However, scab resistance should not be the only consideration in selecting crabapple cultivars. Fire blight is a much more devastating disease and has the ability to kill trees within years. Other diseases for which resistant cultivars exist include cedar-apple rust and powdery mildew. It is possible to select cultivars that have the traits you want and have disease resistance—not immunity. In Minnesota, scab and fire blight resistance are the most important type of resistance to consider.

Unfortunately, the literature on disease-resistant cultivars of crabapple is confusing. Publications often contradict each other on whether or not a cultivar is listed as highly resistant to scab. If you recall our disease triangle, you’ll remember that cultivars respond differently to different environmental conditions and possibly to different strains of the scab pathogen, depending on the environment in which the resistance trial is conducted.

Before you decide on any one variety, regardless of what you read, include a trip to the Minnesota Landscape Arboretum to evaluate for yourself how different plants respond to the different disease pressures that are endemic to Minnesota.

And bring a notebook!

Janna Beckerman is the extension plant pathologist at the University of Minnesota’s Yard and Garden Clinic.

Websites featuring information on disease-resistant crabapples: ◆ www.extension.umn.edu/yardandgarden/ ygbriefs/p223fireblight.html ◆ www.extension.umn.edu/yardandgarden/ ygbriefs/p242applescab-crab.html

Winter 2003 • ADVOCATE

Problems with OverMulching Trees and Shrubs

by Patrick Weicherding, Regional Extension Educator–Metro District

Despite these benefits, mulch can literally kill plants if it is applied improperly. A “volcano” of mulch, piled high against the trunk of a tree may not kill the tree immediately, but it can kill over time.

Problems with Over-Mulching Trees and Shrubs

ulching trees and shrubs is a recommended cultural maintenance practice with many benefits. Mulch: ◆ Reduces soil moisture loss via evaporation. ◆ Minimizes weed competition when applied more than 2 inches deep. ◆ Moderates extremes in surface soil temperatures. ◆ Improves plant growth and vigor. ◆ Reduces soil compaction and erosion. ◆ Improves soil aeration and soil structure. ◆ Minimizes frost heaving of small transplants. ◆ May increase soil fertility. ◆ Can reduce salt buildup. ◆ Reduces reflection and re-radiation of heat. ◆ Reduces the incidence of some diseases. ◆ Is aesthetically attractive.

COURTESY PAT WEICHERDING

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Mulch “volcanos”— wood chips piled against tree trunks—are a misuse of mulch that leads to a plant’s decline and eventual death. ◆◆◆

Over-Mulching Can Kill How does over-mulching kill? The most common causes are:

◆ Low Oxygen: Suffocation of tree and shrub roots is the most common cause of death from over-mulching. Repeated applications of mulch can contribute to a waterlogged soil/root zone by slowing soil water loss via ADVOCATE • Winter 2003

Mulching continued on p. 8

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Mulching, from p. 7 evaporation. With water occupying most soil pore space, air content is minimal and diffusion of oxygen is essentially blocked. Roots need oxygen for respiration. When soil oxygen levels drop below 10%, root growth declines. Once too many roots decline and die, the plant dies.

Oxygen starvation is especially common in the spring and the fall, and during other wet periods. Oxygen deprivation is also prevalent in soils that do not have good drainage.

◆ Drought: Improperly applied mulches can actually prevent water from moving into the soil if they are applied in depths that exceed 4 inches and are allowed to dry out. Certain fungi grow in dry mulches, causing it to bind together in large clods. These clods repel water as does a thatch roof on a house. If these dry mulches are applied to dry soils, they can prevent water from penetrating to the root systems of plants. Without adequate water plants become stressed and eventually will die.

◆ Inner bark (phloem) stress: Inner bark death comes from the piles of mulch placed directly against the stem/trunks of trees and shrubs. The root flare stem and trunk tissue is quite different from root tissue—it cannot survive a continually moist environment, and must be able to “breathe” through lenticels in the bark. When mulch is piled near trunks, gas exchange decreases, stressing and ultimately killing the inner bark (phloem) tissue. This also occurs when trees are planted too deep (the root flare is buried).

Once the inner bark dies, roots become malnourished and weakened, with a subsequent reduction in water and nutrient uptake. The entire health of the plant is thus affected. If these conditions are maintained long enough, the phloem tissue may die, starving the roots since they then receive none of the essential photosynthates produced by the leaves.

◆ Fungal and bacterial diseases and opportunistic insects: Most fungal and bacterial diseases require moisture to reproduce and spread. Trunk diseases gain a foothold in the moist, decaying bark tissue under the mulch. Once established, the disease organisms ultimately invade the inner bark, disrupting food transport and finally killing

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the plant. Often this scenario is accompanied by the presence of bark beetles and borers that are also attracted to stressed plants. These expedite the decline and allow entrance of other pathogens into the plant.

◆ Excess heat and hardening-off: The wet mulch layers piled up next to the trunk may begin to heat up when the mulch begins to decompose. This scenario is similar to composting, where temperatures within inner mulch layers may reach 120 to 140 degrees F. This high heat level may directly kill the inner bark/phloem of young trees and shrubs, or may prevent the natural hardening-off period that plants must go through in the fall in preparation for winter. If the trunk flare tissue is not sufficiently hardened off before freezing weather, the tissue may die and the plant will decline.

Other Problems with Over-Mulching ◆ Soil pH: The continuous use of the same type of mulch may also contribute to plant stress by ultimately changing the soil’s acidity level, commonly referred to as soil pH. Acidic mulches like pine bark may have a pH of 3.5 to 4.5 and when applied year in and year out, may cause the soil to become too acidic to grow many alkalinerequiring plants. Due to the increased solubility of many micronutrients in acidic soil, toxic levels of micronutrients may lead to additional plant stress which in turn allows secondary pathogens and insect to invade. Conversely, hardwood bark mulch, which is initially acidic, may cause the soil to become too basic or alkaline, causing acid loving plants to quickly decline because of micronutrient deficiencies. Soil pHs above 6.5 to 7.0 usually create micronutrient deficiencies of iron, manganese, and zinc for many common acid-loving, landscape plants. Small changes in soil acidity can be avoided by periodically monitoring soil pH and rotating the type of mulch used.

◆ Rodent chewing and girdling: Piles of mulch next to the trunk may also provide cover for chewing rodents such as mice and meadow voles. These rodents live under the warm mulch in the winter and chew on the nutri-

Winter 2003 • ADVOCATE

◆ Nutrient deficiencies and toxicities Many “green” or non-aged types of mulch may cause nitrogen deficiencies in young trees and shrubs. Decomposing bacteria and fungi which ultimately break down mulch must have an ample supply of nitrogen to do their job. Most landscaping mulches are composed of bark or wood residue which have high carbon to nitrogen ratios and have very little nitrogen available for the decomposing bacteria. Hence, the bacteria in the soil utilize the existing nitrogen to break down the mulch. This process may cause nitrogen deficiencies on new growth. Although nitrogen deficiencies may occur, they are usually considered temporary as the mulch will eventually release its nutrients into the soil and the decomposition will taper off.

◆ Anaerobic or “sour” mulch “Sour” mulch can occur when finely ground mulch is piled so high (usually greater than 10 feet) that inadequate air exchange occurs in the center of the pile. Without adequate oxygen, anaerobic microorganisms become active and produce several organic acids and alcohols, causing the mulch to give off pungent odors and produce extremely acidic pHs ranging from 1.9 to 4.8. Such mulch is highly toxic to plants—especially recently transplanted woody ornamentals.

If mulch smells bad or is extremely acidic, don’t use it until it is properly composted.

◆ Allelopathic mulch: Allelopathic toxins are compounds produced by plants that inhibit the growth of other plants.

Such substances might be present in mulch, depending on the source. The classic example of allelopathy is the black walnut (Juglans nigra). It produces juglone and juglonic acid, which inhibit the growth of many plants. Juglone is found in all parts of the plant. Therefore, fresh wood chips and sawdust from black walnut should not be used as mulch unless well composted. Even then, small amounts of juglone can be detected.

Besides black walnut, other allelopathic mulches include uncomposted sawdust of red-

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wood (Sequoia) and cedar (Cedrus); the bark of spruce (Picea), larch (Larix) and Douglas fir (Pseudotsuga).

Standard Mulch Recommendations Mulching is one of the best—and maybe one of the worst—things you can do for your trees and shrubs. Mulch depth should not exceed 3 inches as a standard. However, on poorly drained soils, mulch depths should not exceed 2 inches, especially for shallow rooted plants. Wet soils may not need any mulch. Coarser-textured mulches can be placed a bit deeper due to better oxygen diffusion into the soil. Finer-textured mulch, such as double-shredded mulch, may need only a 1- or 2-inch layer.

If you have a problem with excess mulch, dig through the landscape to see how deep the mulch really is. A light raking of existing mulch may be all that is needed to break through the crusted or compacted layers that can repel water. Pull mulch back from plant stems and trunks—a rule of thumb is 3 to 5 inches away from young plants, and 8 to 12 inches away from mature tree trunks. Visually look for the presence of a root flare; if not visible, it may be at least partially buried and must be exposed.

Remove all soil or mulch up to the junction of the roots and trunk collar (taking care not to damage the tender bark) to expose the root collar. Leave the resulting well open and exposed to air. Research shows that an amazing number of plants have rapidly improved in color and vigor within months of root collar excavations.

In conclusion, mulch may be “worth its weight in gold” but improperly used it may be “too much of a good thing.”

JIM KIEHNE

tious inner bark. This often goes unnoticed until the following spring when the “tree doesn’t look so good.” If the trunk is girdled (that is, over 50% chewed around the trunk), there is little that can be done to save the plant outside of bridge grafting.

Mulch should be pulled back several inches from tree trunks, resulting in a doughnutshaped circle of wood chips. ◆◆◆

Patrick Weicherding is a Regional Extension Educator with the University of Minnesota Extension Service working out of the Anoka County Extension Office in Andover, Minnesota.

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“Buckthorn Busting” Invades Minneapolis Neighborhoods

by Paula Denman

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riginally planted because it was a tough, reliable landscape plant that grew well in a variety of situations, buckthorn has naturalized and now grows throughout the northeastern and north central third of the U.S. It has proven so adaptable to the wetlands and woodlands in Minneapolis that it warrants its own “watch” program, and has inspired the Minneapolis Park and Recreation Board to institute five-year eradication partnerships with residents.

Reclaiming and protecting our natural areas requires a long-term commitment from many communities and entities. Throughout the Twin Cities a collaborative effort to control buckthorn is underway, with the Minneapolis Park and Recreation Board spearheading the effort as they try to gain the upper hand on the land they manage. When three neighborhoods decided to sponsor buckthorn removal projects, they looked to the experience of the St. Anthony Park neighborhood in St. Paul. Using this as a model, each neighborhood designed their own version of the St. Anthony Park Buckthorn Roundup.

The St. Anthony Park Model Mary Maguire Lerman, horticulturalist for the MPRB, was one of the organizers for the St. Anthony Park Buckthorn Roundup in the summer of 2000. For the St. Paul roundup, $800 in funding was donated by the St. Anthony Park Association and the St. Anthony Park Garden Club.

Their roundup was held on the first Saturday in November, and it took volunteers with a chipper and truck 12 hours to remove the brush stacked curbside at 75 homes. Originally offered free to residents, the roundup was so popular that the costs were double the available funding.

Organizers contacted participants after the roundup to request a $10 donation per household.

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To help other neighborhoods get started with buckthorn removal projects, St. Anthony Park put together a packet of information based on their experience. The packet offered guidance on how to go about organizing a roundup, where to find funding, and how to treat buckthorn so it doesn’t regrow from the roots after the rest of the plant has been removed.

Partners & Preparation To support the three neighborhoods with their fall 2001 roundups, the University of Minnesota Hennepin County Master Gardener Program and the Minneapolis Park and Recreation Board trained Master Gardeners and neighborhood volunteers to identify three widespread invasives—buckthorn, mulberry and tartarian honeysuckle. During September and October, volunteers conducted visual surveys of private property from public sidewalks and alleys. Wherever invasives were identified, a door hanger was left. The door hanger included a map indicating the location of invasives on the property, information about that neighborhood’s removal project, and the name and phone number of the coordinator to contact for more information.

The neighborhoods chose different weekends for their roundups to allow survey volunteers to take part in more than one area. Prospect Park limited their project to buckthorn, the most common invasive in the area. Fulton and Linden Hills chose to include mulberry and honeysuckle along with buckthorn.

The Prospect Park East River Road Neighborhood In Prospect Park, the removal was sponsored by the Landscaping Committee and Garden Club of the Prospect Park East River Road Improvement Association. Funding sources included the Neighborhood Revitalization Program ($2,000), a USDA Forest Service Grant ($1,000 reimbursement grant), and a grant from the Community Action Cooperative Association ($400). I was hired as project coordinator, and our goal was to sponsor annual pickups for 10 years.

The roundup was publicized by flyers handed out at National Night Out block club parties, through a series of articles in The Southeast Angle, the neighborhood association newsletter, and through the doorhangers left by surveyors.

Twelve volunteers completed a survey of the neighborhood before the roundup date. The cutoff date to sign up was one week before the pick-

Winter 2003 • ADVOCATE

COURTESY MINNEAPOLIS PARK AND RECREATION BOARD

Buckthorn removal and chipping in the Linden Hills Neighborhood ◆◆◆

up date, and a $15 fee was requested per stop.

Participants received packets with instructions about how to cut and stack brush, and how to treat the stumps after cutting. Free home visits by trained volunteers were offered to residents who needed help identifying plants that might have been missed by surveyors. Twenty-eight homes signed up to participate.

A rear-loader compactor truck was hired from Aspen Waste Systems for $100 per hour, and NRG Processing Solutions, LLC, which is located in the neighborhood, disposed of the brush at no charge. The pickup began at 9am on Saturday October 6 and was completed just after noon.

Pickups were made by address, but volunteers could pickup unscheduled brush if they had time.

The truck driver worked alongside volunteers to load the truck, and 3 volunteers worked each of the two 2-hour shifts. A compactor truck reduces time lost in emptying non-compacting trucks, and saves time that would be spent in chipping, but compacting brush was slow. While waiting for the truck to compact each batch, volunteers were busy sweeping up twigs and thousands of berries.

The Fulton neighborhood Financing for Fulton included Neighborhood Revitalization Program funds ($6,000), a USDA Forest Service Grant ($1,000), and Minnesota Department of Natural Resources Conservation Partnership Grant ($4,000). Fulton chose to go with a free curbside pickup for 3 years, with a goal of 50 households participating per year.

Michelle Mensing, Neighborhood Coordinator, was in charge of their project.

Sixty households participated in the roundup.

Fulton completed surveying 2/3 of their 2,000 households before their roundup, and twenty residents had already signed up before the survey.

Coordination of the event was handled by a 4-person committee, 10 volunteers surveyed private property, house calls were offered to residents, and 6 volunteers worked on the pickup

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day. Residents donated the use of a truck and chipper.

There was no formal cutoff date to sign up, but due to the high participation, applications were cut off two days before the pickup date.

Curbside pickup was scheduled by address, although brush not on the signup list was picked up along the way as well.

Pickups started at 7am on Saturday and continued until dark, about 7pm. An additional 3 hours were needed on Sunday to complete the collection. Equipment problems slowed things down because the truck and chipper were unable to keep up with the continual demand. Next time they plan to hire a professional tree service to handle hauling and chipping.

Mensing believes that their “multi-angle” approach to publicity was important to their high participation. They received the best response from the door hangers left during the In 2002, removal of bucksurvey, and their neighthorn from private property took borhood billboard was place in the Prospect Park, next in effectiveness.

Seward, Howe, Cooper, Hiawatha, Additionally, posters, Linden Hills, Fulton, and the East community newspaper Harriet Farmstead neighborhoods. articles, sandwich signs, In addition, residents helped the and the neighborhood Minneapolis Park and Recreation organization’s bimonthly Board remove buckthorn from newsletter all helped Cedar Lake and the Cedar Lake raise awareness of the Trail, West River Parkway, Spring buckthorn problem and Lake, William Berry Park, Lake the upcoming roundup.

Harriet Parkway, Minnehaha

Update 2002

The Linden Hills Neighborhood

Creek, Diamond Lake and the Mississippi River Gorge.

In Linden Hills, the response was so great—over 168 residences participated—that the pickup stretched over 4 days. Next time, Madalin Cioci, Linden Hills Neighborhood Council Implementation Coordinator, plans to keep it to one day. Funding included a USDA Forestry Service Grant ($1,000) and a Minnesota Department of Natural Resources Conservation Partnership Grant ($8,000). Plans are to hold roundups each year for the next two years.

Buckthorn continued on p. 12

11

Buckthorn, from p.11

12

Publicity for the roundup included information in the association newsletter, which is sent to every household in Linden Hills, and an article in the Southwest Journal about the invasive nature of buckthorn and the upcoming roundup.

When 32 volunteers surveyed the area, they also knocked on every door to offer to do checks of backyards. This was popular with residents and gave the surveyors a chance to do more complete inventories than was possible in the other neighborhoods, but it also required much more time.

Three-fourths of the survey was completed in time for the roundup.

Weather was uncooperative, and volunteers worked in the rain on roundup day. The clam truck they used (also called a Prentis Loader) had a pick-up arm that quickly collected brush, but required that it be gathered into large piles to be effective. The collection arm cannot reach far enough to go over vehicles to reach the curb, so “NO PARKING” signs were purchased from the Traffic Division of the City Street Department and volunteers placed them in front of each scheduled stop ahead of time. Wet brush tended to stick in the chipper chute and, even with 18 volunteers, the roundup took 4 days. As in the Fulton neighborhood, costs skyrocketed and they requested donations of $10 to $30 per home after completion of the roundup.

do not have to pick up brush that hasn’t been cut and bundled, they often go beyond the call of duty and pick up anything left curbside. Having the city collect part of the brush would make accounting difficult when you are picking up by address or are charging for the roundup.

Mensing suggests that you not schedule a roundup during a Gypsy Moth quarantine. They found out about the quarantine 2 weeks before their pickup date. After the initial panic subsided, arrangements were made by the MPRB to have the chipped material burned, and the project went on as scheduled.

Both Mensing and Cioci found surveying for 3 invasive species was confusing for volunteers and residents. Some plants were misidentified by surveyors, and Cioci would like for volunteers to receive more extensive training before going into the neighborhoods.

All three coordinators agreed that using multiple forms of advertising to educate residents and raise awareness was important to getting people involved. The door hangers were the most effective method for all three. Cioci plans to add a signup form to their website next time to reduce registration time, and will consider ways to let residents take charge of keeping cars from parking at their curbs, rather than recruiting volunteers to put out signs.

Words of Wisdom

Next Steps

All three neighborhoods successfully recruited volunteers to help with all phases of their roundups, but relied on paid coordinators to keep things on schedule. Mensing said that the use of paid staff allowed for good accountability, and made it possible to provide residents with one-onone contact that would not be available if relying entirely on volunteers.

Cioci disliked having to ask for donations after the roundup and thinks it is better to charge a nominal fee up front for participation. In Prospect Park, the only comments received about the $15 fee was about how reasonable it was. Some residents worried that they had so much buckthorn at the curb, that we wouldn’t pick it all up for only $15. I offered to charge them more if there was “too much,” but it was unnecessary to do so.

I would suggest that, a week or so before a roundup, someone alert Minneapolis Solid Waste to the brush pickup project. Although city crews

Next on the agenda are classes on landscaping and plant selection to help residents prepare for spring planting. Coupons from local nurseries will be given to participants, allowing them to purchase replacement plants at a discount. And, of course, each coordinator will be searching for that pot of gold to finance the roundups for the long term.

Paula Denman is a Minnesota Tree Care Advisor and a University of Minnesota Master Gardener and Plant Health Care Advisor.

Buckthorn Bust Neighborhood Guide ($15), a booklet developed by Tree Trust with funds from USDA Forest Service, will help you put together all the elements of a successful campaign against your community’s buckthorn problem. Contact Tree Trust at 651/6445800, or treetrust@treetrust.org by e-mail.

Winter 2003 • ADVOCATE

URBAN FOREST HEALTH

Forest Tent Caterpillar (FTC) and Your Trees Minnesota Department of Natural Resources

F

orest tent caterpillar in 2003: What’s on the menu?

The forest tent caterpillar (FTC), Malacosoma disstria, is a native defoliator of hardwoods, especially, aspen and birch trees in northern counties and basswood and oaks in central and southern counties. Forest tent caterpillars are often mistakenly called “armyworms”.

In the forest, FTC defoliation usually does not affect tree health because FTC populations usually collapse before tree damage occurs. FTC can consume 60% of a tree’s foliage for three years and the tree will show no ill effect. Even completely defoliated trees will usually develop a second set of leaves in mid-July without a loss in health.

Widespread outbreaks of FTC occur at intervals of ten to twenty years and are two to four years in duration. Outbreaks peaked in 1922, 1937, 1952, 1967, 1978, and 1990. Populations collapse due to starvation, predation and parasitism. Populations of the “friendly flies” (see sidebar), native parasites, build up as the FTC populations peak.

About 7.7 million acres were defoliated statewide in 2001. Hopes were for a decline in 2002, though extensive defoliation was still expected.

The friendly fly A major parasite of the forest tent caterpillar is the friendly fly, Sarcophaga aldrichi. It is small, and gray to black in color. Its face has hairy sides, its thorax has three black stripes and its abdomen is checkered. As its name implies, the friendly fly does not bite. Unfortunately, it tends to regurgitate on peoples’ skin, clothes, picnic tables, foods and clothes drying on lines.

You may see an abundance of the friendly fly. But the adults are not the parasites, as they only feed on various sugarcontaining materials such as nectar, sap, fruit juices, and aphid honeydew. The maggots (larvae) of this fly are the parasites of forest tent caterpillars. Maggots are deposited on forest tent caterpillar cocoons where they penetrate the silk, chew into the prepupae or pupae, feed on caterpillar tissues and eventually cause their death.

Several other species of smaller flies and certain wasps feed directly on or parasitize eggs, caterpillars, or pupae of the forest tent caterpillar. Predatory beetles, ants, true bugs, spiders, birds, and small animals, as well as viral and fungal disease organisms also serve as biocontrols.

FTC in 2002 The summer of 2002 brought the most serious defoliation in northern Beltrami County since 1954. Yet, the expected defoliation predicted in and around the city of Bemidji did not occur. Aspens, birch, and other hardwoods refoliated.

The stench of rotted larvae in the heavily defoliated areas slowly disappeared.

FTC in 2003 Surveys of forest tent caterpillar egg masses in central and northeastern Minnesota predict a sharp drop in caterpillars for most areas. The caterpillar population will be high, however, in Deer River, Hibbing, Virginia, Finland, and Gooseberry Fall State Park.

In addition to the egg mass survey, there are other clues that the forest tent caterpillars will decline in 2003. When the larval surveys of 2001 and 2002 were compared, the 2002 survey showed more dead caterpillars, killed by disease, in more locations. There was also a great increase in the number of parasitic flies. These flies mark “the beginning of the end”. They deposit living maggots on FTC cocoons. The maggots chew through the caterpillars’ exoskeleton and feed on internal living tissues. Thus, the caterpillar is killed.

An early July collection of more than 100 cocoons from ten areas in central and northeastern Minnesota found a great increase in cocoon ADVOCATE • Winter 2003

Forest tent caterpillars ◆◆◆

FTC continued on p. 14

13

FTC defoliation in 2002

When do the FTC hatch?

Egg masses of the forest tent caterpillar encircle twigs, are covered with a frothy, glue-like substance, and are bronze to dark gray in color. Each mass contains up to 300 eggs.

To determine the effects of temperature and dormant oil on hatching the following experiment was set up during the winter of 2001-2002 on 40 egg masses collected in the summer. Sixteen egg masses were sprayed with a dormant oil labeled for use on FTC egg masses. All others were not sprayed. Each egg mass was placed in a window-pane envelope.

Then the egg masses were either kept at room temperature or kept outdoors in the shade.

Numbers of caterpillars that hatched and lived

Indoors Outdoors

parasites. In August, the moths, parasitic pupae, adult wasps, and diseasekilled caterpillars were counted. The following table shows some of the results of this study. A similar study performed in 2001 found an average of 24% of the moths had emerged.

Caterpillar-to-Moth Success in 2002: % of moths emerged Hibbing 2 Floodwood Deer River 10 Two Harbors Grand Rapids 9 Cloquet Fr. Hennepin State Park 2 NE Duluth Bay Lake, Aitkin Co. 3 Gooseberry Fall State Park

7 4 5 3 5

Average: 5% We think the outbreak is nearly over and there will be a sharp drop in the overall population of FTC in 2003. There will be some areas, however, where FTC will survive in bothersome numbers. This will be true where they have expanded into new areas and where their natural enemies (disease pathogens, parasitic flies, etc.) are minimal. FTC could also remain a problem where night lights attract egg-laying moths from surrounding areas, thus concentrating them on nearby trees and shrubs.

Not sprayed Sprayed with oil with oil All lived None lived All lived 5 lived

Conclusions: ◆ At room temperature, most FTC hatch within 14 days.

◆ Dormant oil spray is useful in preventing FTC from hatching and can kill most of the caterpillars that do hatch.

Approximate schedule* for FTC life stages and host tree foliage: Host tree buds break Apr 18–May 10 FTC hatch Apr 18–May 15 FTC major feeding period June 5–June 25 FTC pupate End of June Host trees refoliate Early to mid-July FTC moths fly and lay eggs July 1–July 15 * The timing of biological events varies from year to year because timing depends on weather and location. For example, events will occur near the earlier date: when the spring is early; when May and June are hotter than average; or, when the location is south of Mille Lacs Lake.

More information on FTC and color photos can be found on these websites: ◆ www.dnr.state.mn.us/treecare/forest_health/ftc/index.html ◆ www.extension.umn.edu/distribution/horticulture/DG7563.html ◆ www.na.fs.fed.us/spfo/pubs/infosheets/tentcat/index.htm

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Winter 2003 • ADVOCATE

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: Lorrie Stromme, City of Minneapolis—612/788-5157 Vice President: Michael Max, EnvironMentor Systems, Inc. —763/753-5505 Rich Hauer, MN Dept. of Agriculture—651/296-0592 Jim Hermann, Mpls Park & Rec Board/Forestry—612/370-4900 Ken Holman, DNR/Forestry—651/296-9110 Fletcher Johnson, Xcel Energy—651/639-4590 Gary R. Johnson, U of M/Forest Resources—612/625-3765 Robert Slater, MN Dept. of Transportation —507/529-6145 Kathy Widin, Plant Health Associates, Inc.—651/436-8811

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 —218/326-7600 Secretary/Treasurer/Technical Advisor: Dan Jordan, IRRR–Mineland Reclamation—218/254-3369 Coordinator: Kathleen Preece, Minnesota BetterFORESTS magazine—218/326-0403 or kathleen@uslink.net.

ADVOCATE • Winter 2003

Calendar

URBAN AND COMMUNITY FORESTRY CALENDAR

Events

March 25-26—Minnesota Shade Tree Short Course. Bethel College, Arden Hills, MN. Nicole Hettwer, 612-624-2705, or nhettwer@cce.umn.edu June 24-25—Minnesota Vegetation Management Association of Minnesota (VMAM) Conference. University of Minnesota–Morris, MN. Contact: Vicky Dosdall, 320/795-2412; vttd@runestone.net or Paul Walvatne, MNDOT, 651/284-3793; paul.walvatne@dot.state.mn.us August 6-9—International Society of Arboriculture Annual Conference. Montreal, Quebec. www.isa-arbor.com September 17-20—National Urban Forestry Conference.

San Antonio, Texas. www.americanforests.org September 21-28—XII World Forestry Congress. Québec City, Canada. www.wfc2003.org October 25-29—Society of American Foresters National Convention. Buffalo, New York. www.safnet.org

MnSTAC Meetings Upcoming meetings are February 20, March 20, April 17, and May 15; locations vary by meeting. Info at MnSTAC’s website (www.mnstac.org).

New Publications Brooklyn’s Urban Forest. D. J. Nowak.

2002 USDA Forest Service. Northeast Research Station. 359 Main Road, Delaware, OH 43015 Gen. Tech. Rep. NE-290 Our Heritage of Community Trees. Henry D. Gerhold and Stacy A. Frank. 2002.

Pennsylvania Urban and Community Forestry Council.

The Ecology of Plants. Jessica Gurevitch, Samuel M. Scheiner, and Gordon A. Fox. 2002. Sinauer Associates.

Trees for Children: Helping Inner City Children Get A Better Start in Life, Technology Bulletin 7; www.urbanforestrysouth.usda.gov/ pubs/Tech_bulletin/ Kids_Trees_Tech_Bulletin7.pdf

Trees on the Internet Winter doesn’t last forever, and Arbor Day is just around the corner. Get up-to-date information from the National Arbor Day Foundation’s website (www.arborday.org).

E-Nature includes field guides to 4800 North American plant and animal species. www.enature.com Seedling Source, National Tree Trust’s electronic newsletter. www.nationaltreetrust.org The Overstory is a free noncommercial e-mail journal. Each issue focuses on a concept for agricultural systems which integrate trees and other perennial plants. www.agroforester.com/ overstory/osprev.html The Human-Environment Research Laboratory at the University of Illinois (www.herl.uiuc.edu) has useful information and factsheets on human responses to urban green space, such as reduction of crime, moderation of ADHD symptoms, and improved self-esteem in adolescent girls.

Check out the information on landscaping for crime prevention at Blue Ridge Community College’s site (www1.br.cc.va.us/murray/ research/cpted/default.htm).

Interested in information on street tree inventory programs that use PDAs (Palmpilot, etc.) to manage data in the field? www.umass.edu/urbantree/ palm/index.htm is worth a look.

For handy up-to-date links to websites 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, Cindy Ash, Mark Stennes, Jeff Rick, Don Mueller, Rich Hauer, Gail Nozal, Patrick Weicherding and James Burks) Editor-in-Chief: Judy Slater judyslater@earthlink.net Design: Jim Kiehne 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: Judy Slater Minnesota Shade Tree Advocate 115 Green Hall 1530 Cleveland Ave. N. St. Paul, MN 55108

Award Winners Congratulations to the 2002 Minnesota Society of Arboriculture award winners:

◆ Jean Albrecht – Award of Merit (U of M) ◆ Judy Hanson – Treescaping Award (Nicollet County Commissioner) ◆ Jim Hermann – Treescaping Award (Minneapolis Park & Rec Board) ◆ Mary Jo Roth & Byron Johnson – Corporate Award of Excellence (Great River Energy) ◆ Mark Stennes – Distinguished Service Award ◆ Tou Vang – Volunteer Service Award ◆ Paul Walvatne – 2002 Practitioner’s Award (MNDOT) ◆ Barbara Zins – Volunteer Service Award ◆ Mike Zins – 2002 President’s Award ◆ Mike Zins – Toothless Saw Award

Printed on recycled paper using soy-based inks.

Minnesota Shade Tree Advocate 115 Green Hall 1530 Cleveland Ave. N. St. Paul, MN 55108 RETURN SERVICE REQUESTED

New Minnesota ReLeaf Grants Recommended by LCMR The Legislative Commission on Minnesota Resources (LCMR) has recommended that the MN ReLeaf Community Forestry Grant Program be funded at $800,000 for fiscal years 2004 to 2005 ( July, 2003 to June, 2005). Pending final approval by the Legislature and Governor, matching grants of up to $15,000 to local units of government, schools and non-profits will be available for projects including: ◆ Forest Health ◆ Community Forest Inventories ◆ Tree Planting Application packets will be available by the Shade Tree Short Course, March 25, 2003, with full applications due in mid-June. View the guidelines and a pre-application at www.dnr.state.mn.us/fad/ forestmgmt/releaf.html or call DNR Forestry at 651/297-3519 or Tree Trust at 651/644-5800.

Help Pay Postage!

The MnSTAC membership recently approved a policy (on a trial basis) to charge $10 for an annual subscription to the Advocate newsletter. Checks can be made payable to “University of Minnesota” and sent to Gary Johnson, 115 Green Hall, 1530 Cleveland Ave. N., St. Paul, MN 55108. The purpose of the voluntary subscription fee is to help cover postage and production costs.

Presorted Standard U.S. Postage PAID Permit No. 171 St. Paul, MN

Winter 2003 • ADVOCATE