Tre e C a re A d v i s o r N ew s l e t t e r http:// www.mntca.org Inside This Issue:
Quick Hits Mulch!
Press Release: Gypsy Moth Traps Invaders Reshape the American Landscape After Years of Blight, Elms Rebound What’s New Online? Thriving in the Midwest Ash: Mystery Solved Volunteer Opportunity American Bladdernut TCA Accolades and a Volunteer Opportunity Printable Letters and The New Guy Native Species: Best Choice? Arboriculture Myths: 1) Staking 2) Bigger is Better 3) Fixing Compaction Contacts
Volume 9 Number 2
Gary Johnson and Dave Hanson, Managing Editors
Hey,Tree Care Advisors You're invited . . .
federal agency reps. Free subscription to The Shade Tree Advocate newsletter. 2 to join the Minnesota There is a large amount of inHow do you join? Shade Tree Advisory Commitformation out there regarding Just attend a MnSTAC program tee (MnSTAC) 3 mulching. Some of it might and be welcomed as a new What's MnSTAC ("Minnmember. Membership is open stack")? make very good mulch. Spread MnSTAC is the urban to people actively involved in 6 it thin, spread it thick, use orurban & community forestry, forestry council in Minnesota, ganic, use synthetic, add nitro- advising the State Forester, de- based on their professional experience, community involvegen, use a fabric: How is a per- cision-makers, and the public ment, or advocacy. That inabout the health and well-being 8 son supposed to know what to cludes us! of community trees. And it do? provides a forum for exchanging When? 8 Gary says: “Hey y’all check out and communicating information MnSTAC members meet the 3rd and experiences about commu- Thursday of each month this excellent mulching pub nity forestry. [More informa(except August). The next option at: www.mnstac.org ] from our friends at the Iowa portunity is Thursday, June 9 What's in it for you? 20th, at 9:30 a.m. on Nicollet State University. It’s informaLearn the latest tree informaIsland (De La Salle High School) 9 tive, accurate and beautiful all at tion directly from the experts . . in Minneapolis, when Gary Johnthe same time.” . before it's even published. son will lead a field tour of a It's free!!! No membership fee. brownfield tree-planting project The URL to the Adobe Acroand report on the trees' health 10 Rack up TCA volunteer hours! bat .pdf is: http:// two years after being planted. Network with your peers and (Check the web site for future www.extension.iastate.edu/ 11 other tree people - your meeting locations.) Publications/SUL12.pdf schmoozing may lead to rePlease join me at a future warding volunteer opportuniCheck it out! MnSTAC program! ties! Lorrie Stromme Meet city foresters and state & 12 TCA & MnSTAC member 13 Insect damage? Disease? Abiotic? What: A field tour to help you brush up on your diagnosis skills re: plant id, insect pests, tree diseases, and abiotic problems. Also, bring along samples of plant prob14 lems the experts! 15 FREE brats, beverages, salads, etc., after17 ward ( talk one-on-one with the experts and avoid rush-hour traffic!) 20 When: Tuesday, August 20, 3:30 to 6-ish
Who: Our field tour leaders: Dr. Cindy Ash, plant pathologist, American Phytopathological Society Val Cervenka, plant health specialist, MN Dept of Agriculture Gregg Hove, Eagan City Forester Where:Blackhawk Park, 1629 Murphy Parkway, Eagan RSVP: Lorrie Stromme, stro0293@umn.edu or 612-788-5157
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News Release: Minnesota Department of Ag- actually interfere with officials’ riculture efforts to control the gypsy
90 West Plato Boulevard, St. Paul, Minnesota 55107 (651) 297-1629 FOR IMMEDIATE RELEASE: Monday, April 22, 2002 Contacts: Ryan Benbo, Communications Coordinator, 651-2840279 or Kimberly Thielen Cremers, Gypsy Moth Coordinator, 651-296-6692
MDA asks homeowners not to place store-bought gypsy moth traps on their property
moth.
“Gypsy moth traps are not an effective way to eradicate gypsy moth populations,” Thielen Cremers said. “We simply use traps to monitor for the pest and determine if more intensive management efforts need to be taken at certain locations. When homeowners post their own traps, population numbers may be skewed. This could impair our ability to detect a problem and react accordingly.” The MDA, in cooperation with the U.S. Department of Agriculture, has had an annual gypsy moth trapping program in place since 1973. This program is designed to protect Minnesota’s forests from this invasive tree pest that has defoliated forests in Wisconsin and other eastern states.
Traps placed by homeowners may impair monitoring Each summer, MDA workers efforts that protect fan out across the state to set Minnesota’s forests
A female gypsy moth on an egg mass.
about 15,000 gypsy moth traps. These traps, known as delta ST. PAUL, Minn. – As the Min- traps, are tent-shaped pieces of nesota Department of Agricul- cardboard that are stapled or tied to trees and poles. Each ture (MDA) kicks off another season of gypsy moth trapping, trap contains a pheromone designed to lure adult male homeowners are being asked not to place on their property gypsy moths. Once inside, the moth gets caught in a sticky any gypsy moth traps other than those posted by the MDA. substance coating the trap’s interior. All traps are monitored by the MDA and are removed at the end of the seaThis request comes after the son. MDA discovered that some home and garden retailers are beginning to sell gypsy moth traps. There is no law against homeowners buying gypsy moth traps and posting them on their property, but MDA Gypsy Moth Coordinator Kiberly Thielen Cremers said that posting private traps may
Gypsy Moth Trap Photo courtesy of MDA
Traps are placed at a rate of between one per square mile and one per four square miles as a method of detecting new infestations. They are placed at higher rates in areas where male moths were caught in previous years. Whenever possible, traps are placed on public property or on public rights of way and private property. Private landowners are asked for permission to place a trap on their land. Traps placed on private property are immediately removed if landowners object. The traps are labeled with MDA insignia for easy identification. For more information about the MDA’s gypsy moth program, call the Gypsy Moth Hotline at 651-296-MOTH (Metro) or 1-888-545-MOTH
(Greater Minnesota). This release is available on the MDA website at http://www.mda.state.mn.us
In accordance with the Americans With Disabilities Act, an alternative form of communication is available upon request. TTY 1-800-627-3529
Invaders Reshape the American Landscape From the New York Times February 5, 2002 By CAROL KAESUK YOON In the summer of 1904, Hermann Merkel, the chief forester at the Bronx Zoo, noticed that a few of the majestic American chestnut trees lining the zoo's walkways had developed a mysterious new disease. The next year, nearly every chestnut tree in the parks of the Bronx had the disease. And by the 1950's it had spread from Maine to Georgia, killing billions of chestnut trees and changing the East's wooded landscapes forever. Merkel had discovered the disaster known as chestnut blight, giving scientists their first bitter taste of the imported diseases that have been sweeping through American forests ever since. The best known are chestnut blight and Dutch elm disease, both of which are believed to have come from Asia and are still attacking trees today. But scientists say a host of devastating forest pathogens have continued to arrive. Among the most recent is sudden oak death syndrome, which has killed thousands of oaks and other trees in California and may threaten the mighty redwood as well. Fast-moving and usually hard or impossible to cure, these exotic diseases have destroyed countless trees in forests, cities and suburbs. The results can be seen not only in landscapes stripped of some of
their most beautiful species but in changes to how forest ecosystems work and in the economic value of this natural resource. "I get concerned about what the forests of the future will look like," said Dr. Craig G. Lorimer, a forest ecologist at the University of Wisconsin. "To have so many diseases cause so many problems over such a short period of time is really unprecedented. You get this impression that clearcutting is the most devastating thing that's ever happened to North American forests, and it's not. This is much more serious." As world trade intensifies, scientists predict that more and more tree diseases will find their way into the country (and out of it). And while most pathogens die on arrival, unable to find a suitable victim or climate, a small portion turn into devastating blights. According to a report last month from the National Academy of Sciences, about 13,000 plant diseases a year are intercepted by inspectors at international ports of entry — and these inspectors are able to examine perhaps 2 percent of the incoming cargo and baggage. The effect of such invasions is clear. A fungus called dogwood anthracnose has killed millions of flowering dogwoods in the southern Appalachians alone, essentially wiping out the species in many areas. In the Southeast, butternut canker has hit butternut trees so hard that the species has been listed as threatened in at least one state, Tennessee, and has been declared a species of special concern, a prelude to consid-
eration for federal listing as threatened or endangered. In the Northwest, an imported root disease is killing off Port Orford cedars, whose wood can be worth as much as $50,000 for a single, mature tree. And the list goes on. If imported insects are included among the pests, the casualty list grows even longer; some species are attacked by both kinds of imported pest. Dr. Don Goheen, a plant pathologist with the United States Forest Service in Medford, Ore., who works with Port Orford cedars, echoed the comments of others, saying: "These introduced diseases are bad news. We're run ragged by them." Though the devastation goes on around the country, it has received little notice outside the community of forest researchers — largely, scientists say, because a diseased tree can take years to die and its loss is not always evident to the casual observer. "When you look out there you don't have a barren moonscape," said Dr. Scott E. Schlarbaum, a forest geneticist at the University of Tennessee. "You have a forest. But that forest is very different than it was 100 years ago."
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Invaders Reshape the American Landscape
The loss is most likely to be noticed when the tree is prized for its beauty. The rapid spread of dogwood anthracnose, a fungal disease that begins with spotting leaves and soon ends in the death of the tree, has robbed many communities of flowering dogwoods, long a joyful herald of spring. Dr. Mark Windham, a plant pathologist at the University of Tennessee, says the disease is attacking Pacific dogwoods in the West and flowering dogwoods in the East, with the southern Appalachians hardest hit. In 1989, Dr. Windham said, he saw 20,000 healthy trees on Lookout Mountain in Tennessee go under. "They became fully blighted in two weeks," he said. "In three years most were dead." Researchers estimate that in the Great Smoky Mountains National Park, 60 percent of the dogwoods have been killed by the disease. But even this well-traveled area may not look too bad to the casual visitor: roadside dogwoods do well, exposed to sunshine, which the fungus dislikes. "Tourists don't tend to get out of their cars, so they might not see much," Dr. Windham said. "Several hundred feet into the woods they'd see a different picture." Likewise, dogwoods in sunny yards can escape unscathed. Besides being beautiful, dogwoods play a number of roles in the forest. The leaves have
high levels of calcium, making them a primary food for lactating deer. In addition, the calcium in decaying leaves keeps soils from becoming too acidic, a growing concern now that dogwoods have disappeared from so many areas. And the outer coat of the berries is 20 percent fat, making them a crucial source of energy, for example, for songbirds. Likewise, animals are thought to have suffered when chestnuts disappeared. Before 1900, one out of every four trees in the East was an American chestnut, an abundant hardwood and a hearty nut producer. Dr. Frederick V. Hebard, staff pathologist at the American Chestnut Foundation, a nonprofit organization dedicated to the Herculean task of restoring the tree, says oaks and hickories typically produce hundreds of pounds of nuts per acre — but when chestnut trees were also present, that same acre produced thousands of pounds of nuts. Chestnuts were said to have covered the ground like marbles. The bounty was devoured by chipmunks, voles, bear, deer, turkey, grouse, crows and people. (The roasted chestnuts sold by street vendors generally come from Europe). In the late 18th and early 19th centuries, "people moved here expressly to get land up on Clinch Mountain, where there were so many chestnuts you could set pigs out to forage in the fall," said Dr. Hebard, speaking from the foundation's field station in Virginia. "Before there were ever
cowboys in America, there were pigboys, herding up pigs on horseback and setting them loose to forage." Rare trees are being hit hard, too. Butternut or white walnut trees, which produce a beautiful wood favored by carvers and cabinetmakers, have nearly been wiped out in the Southeast by butternut canker, a fungus whose country of origin is unknown. Among the most worrisome pests from abroad are the various species of Phytophthora, a group of funguslike organisms that includes the culprit that caused the Irish potato famine in the 19th century. Another species of Phytophthora, whose origins remain mysterious, showed up in native forests in the 1950's, attacking the roots of Port Orford cedars. It continues to attack them today. In addition to being a highly valuable commercial wood, these cedars are critical to Northwestern forests. Their fibrous root systems shore up river banks, and their durable wood, once fallen in a river, provides important fish habitat — critical functions where many species of salmon are struggling. Yet another species of Phytophthora has been found to cause sudden oak death syndrome, which has jumped to 14 different plant species since it was first noticed in 1995. Last month, researchers at the University of California reported finding DNA evidence of the disease on dying redwood
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Invaders Reshape the American Landscape
shoots. Scientists are continuing laboratory tests to see whether the new disease can indeed kill this beloved species, or whether something else is doing in the redwood shoots. Sometimes these imported diseases can be treated, if caught early and if enough fungicide is applied or enough limbs are cut off. But such expensive cures are usually attempted only for individual trees on private property. Cures on a forest-wide scale are, in general, impossible. Even curbing the spread of the diseases is difficult, as many travel as tiny wind-borne or water-borne spores or on insects flying from tree to tree. Instead, researchers are seeking to identify and breed disease-resistant trees. In some cases, for example with chestnuts, researchers are creating hybrid trees that are a mixture of resistant foreign species and natives. In other cases, nature itself provides the answer. In Catoctin Mountain Park in Maryland, where nearly all the dogwoods have died, researchers discovered one thriving dogwood whose branches were entwined with several others that had died. That tree has since given rise to a disease- hardy line known as Appalachian Spring, which has just become available for sale. And scientists say one lesson that has come from these blights is the importance of diversity, particularly in planted landscapes. The graceful branches of the Dutch elm, for example, once arched over streets in nearly every city and
town. Scientists say its very popularity may have led to the epidemic. "People came west with this vision that that's what a street should look like," said Dr. George Ware, a tree scientist at the Morton Arboretum in Lisle, Ill. They planted row upon row of the elegant vaseshaped tree, producing a monoculture ripe for an epidemic. "We really brought about the devastation," said Dr. Karel Jacobs, a tree pathologist at the Morton Arboretum. "We loved them too much."
digm has shifted," said Dr. John Castello, a forest pathologist at State University of New York's College of Environmental Science and Forestry in Syracuse. Disease can perform functions like killing weak trees and releasing nutrients for other plants. "The question really is, how much disease is enough?" he went on. "That's what foresters and pathologists are trying to determine now." People, he said, should move from the notion that the only good forest was the one that was here before Europeans arrived. "The idea that everything will remain the same without change is just wrong," he said. "Change is the rule."
As a result, Dr. Jacobs said, researchers urge managers to plant more diversified landscapes to help slow or prevent the spread of diseases. Yet she added that most cities and towns remained worrisomely undiversified, with a handful of favored trees in abundance. Still, hope lives on, even for chestnuts. Dr. Hebard says that in undisturbed forests there are billions of chestnut sprouts that have been growing since the original epidemic decades ago, still too small to be hit by the disease. One promising avenue of research is work on viruses that can attack the chestnut blight fungus attacking the tree. But while many scientists aim for a return to the forests of old, some researchers say that goal is unrealistic. "The concept was always that disease is bad, but that para-
Ulmus Americana
Photos Courtesy of : Virginia Polytechnic Institute and State University, Dendrology Site.
Juglans Cinerea
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After Years of Blight , Elms Start to rebound Anne Raver, New York Times Wednesday, February 13, 2002 Š2002 San Francisco Chronicle More than 70 years after Dutch elm disease began to wipe out 90 percent of the magnificent American elms that lined the streets of so many cities and towns, a handful of resistant varieties are beginning to cast their regal shade over the country's lawns and boulevards. The fungus that causes the disease -- Ophiostoma ulmi -accidentally entered the United States in 1931 on elm logs shipped from France and headed for Cleveland. "It first showed up in Ohio and then New Jersey," said Alden Townsend, a plant geneticist at the National Arboretum for the U.S. Department of Agriculture, who has worked for 30 years to identify and propagate disease- resistant elms. "The fungus is carried from tree to tree by a bark beetle, and soon spread across the country." By the 1980s, the fungus had wiped out 77 million American elms. Now, two native elms are emerging not only as highly resistant (no elm is immune) to the disease, but with the same elegant vase shape and upheld branches that imprinted themselves on the American heart.
The 'Princeton' elm -- first propagated and planted in 1922 by Princeton Nurseries, now in Allentown, N.J. -- may be the prettiest. Several hundred were planted in the early 1930s, to form an allee on Washington Road, leading into the Princeton University campus. And 70 years later, the 60-foot-high trees form the kind of leafy canopy so many Americans had thought lost to history.
However, a resistant elm is not necessarily a beautiful elm. 'Valley Forge' "may not be as nice a looking tree as 'Princeton,' " said Keith Warren, the director of product development for J. Frank Schmidt & Son, a 3,000-acre wholesale nursery near Portland, Ore., that ships 2 million trees a year.
In terms of resistance to Dutch elm disease, the elegant, vase-shaped 'Princeton' is running neck and neck with 'Valley Forge,' a variety selected by Townsend from thousands of elms. WIDESPREAD SEARCH After the disease struck, Department of Agriculture scientists combed the country for resistant elms, propagating the most promising and inoculating them with huge doses of Dutch elm disease. In Townsend's latest test, each tree base was inoculated with 3 million spores of the fungus. (A beetle would transmit up to 100 spores.) " 'Valley Forge' and 'Princeton' showed 96 percent resistance and 'New Harmony' was 86 percent," he said.
'New Harmony' is not getting high marks for beauty either. "It tends to be much twiggier," said Davis Sydnor, a professor of urban forestry at Ohio State University, who is working to bring elms back to Ohio.
Both 'Valley Forge' and 'New Harmony,' Townsend's top selections and planted more than 20 years ago, "are looking good," he said. "They may survive 100 years, but we just don't know how they will do long-term." Photos courtesy of: U.S. National Arboretum Plant Introduction Floral and Nursery Plants Research Unit
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Continued: Elms Rebounding
Still, growers concede, these young trees, like ugly ducklings, may mature into beautiful swans. "The elms are coming very strong," Warren said. Shunned for 75 years because of Dutch elm disease, they are "now coming back as a different group of plants because of research and breeding work." The Schmidt catalog lists 10 elm varieties, though 19 are growing in the nursery. " 'Valley Forge' is going to be very hard to find," Warren said. "The 'Princeton' is probably the best American elm in the most supply." LONGTIME FAVORITE Such promising news gladdens the hearts of urban foresters who have long argued that the elm is about the best street tree there is, despite its susceptibility to disease. When Cleveland was replanting its Public Square in 1978, Sydnor said, "They put a whole bunch of London plane trees in there. They all croaked." The city then tried green ash honey locusts twice and oaks, but Sydnor said, "So here they went through four separate replacements, when I knew the American elm would probably give them at least 15 to 20 years of service as a street tree.". Elm trees are tough, Townsend agreed. "Even if you planted one without disease tolerance, it would tolerate ice and salt, air pollution, drought, some degree of flooding," he said. That's why
the colonists loved them. "People would pull them out of the woods and they would just take off." During the Industrial Revolution, cities found that the elm was one of the few trees that could tolerate "all that particulate matter from burning coal," Sydnor said. "But unfortunately, they planted it to the extreme, which led to a monoculture. Then came Dutch elm disease and the rest is history." About four years ago, the Central Park Conservancy in New York planted a number of 'Princeton' elms at 104th Street and Fifth Avenue, as well as the park's Literary Walk, and they are doing fine so far.
Princeton elm Photo courtesy of: http://www.mv.com/ipusers/env/ princetonelm.html
In 1996, under Sydnor's prodding, Cincinnati planted 70 'Princeton' elms on Martin Luther King Jr. Drive, a highly compacted and alkaline site. They are now 30 feet tall, with trunks 8 inches in diameter. About 300 'Princeton' elms, in fact, have been planted under the Cincinnati elm program, with an additional 100 due for planting this year. Elm lovers may also choose from any number of highly resistant Asian and European hybrids like 'Frontier,' a 40feet-high tree with exfoliating bark and wine-colored leaves in fall; Accolade,' a 70-foot vase-shaped tree with dark green glossy leaves; and 'Allee,' an upright Chinese variety that exfoliates with patches of cream gray, orange and brown.
Frontier elm in fall Photo courtesy of: http://www.coloradotrees.org/ treeomonth/2002/feb_02.htm
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What’s New Online? By Dave Hanson Yes, The column that Marie used to write, along with many other duties, has fallen into my hands. So, look out!
of these are simply in the form of organizations that could use your assistance from time to time. Other postings are for planting events in the near future. Please take a look and make use of these opportunities.
Marie Jones had done a wonderful job getting the TCA website up and running. What that means in reality is that I have no major changes to make. At this point, I am only playing catch-up, making sure dates are accurate.
Marie had pointed out previously that volunteer hour submission is available online. So, I guess “you asked for it, you got it”, volunteer hour submission is available on the website!
Speaking of dates, there are many volunteer opportunities posted to the website. Some
Truthfully, I must admit that in the two weeks that I have been working in this office, I have not visited every portion
of the TCA website. I keep finding all sorts of good stuff that Marie squirreled away online. So, I will leave you with a Marie quote: “If you haven’t checked out the website please validate my job and do it just once. If you are stuck looking for a reference item for tree selection, or need an article that says you shouldn’t compensatory prune at planting time, look online. You would be surprised what you may find!!” Keep those comments and suggestions coming! http://www.mntca.org
Woody Ornamentals Thriving in Midwest ARS News Service Agricultural Research Service, USDA Linda McElreath, (301) 5041658, lmcelreath@ars.usda.gov January 29, 2002 _________________________
Eleven commercially available plants are receiving favorable evaluations by cooperators participating in a project to evaluate ornamental shrubs and trees.
Red osier dogwood
The project, called the NC-7 Regional Woody Ornamental Trials, is a collaborative effort between the Agricultural Research Service and state agricultural experiment stations at more than 30 sites located primarily in the north-central United States, New England and Alaska. Since 1954, the goal of this project has been to identify trees and shrubs that grow well in those regions.
Photo courtesy: VT dendrology
Each year, collaborators col-
lect and submit data to ARS horticulturist Mark P. Widrlechner and his technician, A. Paul Ovrom, who coordinate the trials at ARS' North Central Regional Plant Introduction Station (NCRPIS) in Ames, Iowa. Data are collected for 10 years for each plant. The top 11 accessions, which have good ornamental characteristics and are now available commercially, include nine shrubs: Nugget, a cultivar of the ninebark (Physocarpus opulifolius); Sakakawea, a cultivar of the silver buffaloberry (Shepherdia argentea); Kentucky wisteria (Wisteria frutescensvar. macrostachya); Cardinal and Ruby, cultivars of red osier dogwood (Cornus sericea); Indigo, a cultivar of silky dogwood (Cornus amonum); Konza, a cultivar of fragrant sumac (Rhus aromatica); Tara, a hybrid barberry (Berberis koreana x thunbergii) sold under the trademark Emerald Carousel;
and White Knight hybrid weigela (Weigela florida). Two notable trees are western larch (Larix occidentalis) and Little King river birch (Betula nigra), sold under the trademark Fox Valley. Information on these accessions and many others can be found at the NC-7 Trials web site: http://www.arsgrin.gov/ars/MidWest/Ames/tri alhmpge.html Future plans include testing more woody plants with good adaptation and ornamental merit obtained from populations native to the central portion of the United States. ARS is the U.S. Department of Agriculture's chief scientific research agency. _________________________
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Michigan Ash Disease Mystery Solved ARS News Service
the decline or why the problem was centered in Michigan. They suspected the possible culprit was a disease called ash yellows.
Agricultural Research Service, USDA Linda McElreath, (301) 5041658, lmcelreath@ars.usda.gov January 28, 2002
Mycologist Amy Y. Rossman of ARS' Systematic Botany and Mycology Laboratory in Beltsville, Md., isolated a fungus found on the diseased trees. She and colleague Lisa A. Castlebury used molecular sequencing to show that the fungus was Phlyctema vagabunda, known primarily for causing bull's eye canker of apples. P. vagabunda had been reported on various hardwood and herbaceous hosts from temperate regions, but not on ash trees.
_________________________
A fungal disease caused the demise of ash trees in Michigan's nursery stock last summer, Agricultural Research Service scientists have found. Ash trees became popular for street plantings in the United States after an epidemic of Dutch elm disease killed thousands of elms in the early 1960s. But in Michigan in 2001, young ash trees of the Fraxinus americana (Autumn Purple) and F. pennsylvanica (Champ Tree, Cimmaron and Urbanite) varieties began showing signs of disease in the form of smooth, round, brownishyellow cankers with distinct reddish, cracked margins.
The fungus leaves a characteristic round canker of dead bark that may become discolored, sunken or cracked or may fall away altogether. Often the rest of the branch beyond the canker dies or becomes much less productive. Cankers can attack the bark of trees of all ages.
Although ash trees suffer from many insect and disease problems, arborists in the region weren't sure of the cause of
Identifying the P. vagabunda fungus as one already present
in the United States reduced fears that it might have been brought in from outside the country and could spread even further, or that it would prevent other countries from accepting certain U.S. agricultural products. ARS' identification of the pathogen is the first step toward developing control measures to slow or prevent the decline of ash trees in Michigan. ARS is the chief scientific research agency of the U.S. Department of Agriculture. This item is one of the news releases and story leads that ARS Information distributes on weekdays to fax and e-mail subscribers. You can also get the latest ARS news on the World Wide Web at www.ars.usda.gov/is/pr/thelatest.ht m. * Feedback and questions to ARS News Service via e-mail: NewsService@ars.usda.gov. * ARS Information Staff, 5601 Sunnyside Ave., Room 1-2251, Beltsville MD 20705-5128, (301) 504-1617, fax 504-1648.
Volunter Opportunity: A creative person or a group of creative people are needed to develop a display board. Creators will determine the size of the board(s) and the content. Conferences, meetings, and short courses on Urban Forestry present the opportunity to inform the professional community of Tree Care Advisors and their programs. Accomplishing that goal could be a multi faceted approach. One of the approaches discussed at a recent TCAAG is a durable, stand-alone display board. An ideal board might contain: an
explanation of the TCA program, profile a (fictitious?) tree care advisor, describe typical activities, and outline TCA training topics. Any information selected should be accompanied by pictures and/or graphics. Gary suggested that money could be made available to accomplish this task.
Education
Program
Guiding hands
If you want to take part in this venture in some way, give Dave a call at 612-624-1226 or send e-mail to dlhanson@umn.edu. Tree Care Advisors
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Staphylea trifolia - American Bladdernut By Mike Zins
Leaves and Flowers
Is it any wonder that the plant’s common name, American Bladdernut, challenges the gardening public’s perception of a very useful plant for our landscape! In today’s sanitized world, Bladdernut conjures up thoughts of medical problems and anatomical features we would rather not discuss, let Fruit or capsule alone be planting out in the yard. But beyond the shadow of a comThe Arboretum had a nice mon name that has as little markettree specimen growing in the ing appeal as plugged freeways to small tree collection. It was rush hour commuters, is a native moved to this collection in plant with many desirable features. 1965 and persisted until 1990, It just needs some good press and cause of death unknown. It promotion. reached a height of about 12’, American Bladdernut is as and flowered and fruited heavAmerican as apple pie. It occurs ily for many years. naturally from western Quebec to American Bladdernut Ontario, western New England to has several nice qualities that Minnesota and south to South make it an attractive plant for Carolina and Missouri. It usually our landscapes. In spring the frequents moist, wooded areas and oppositely arranged, nearly ravines in the southern part of Minround buds open giving rise to nesota, as far north as Ramsey pinnately compound leaves, County and westward to the New each consisting of 3 leaflets. Ulm area. The genus Staphylea has The dark green leaflets with about eight species found growing their trifoliate arrangement in north temperate areas, two of account for the species name which are native to North America. trifolia. After the leaves have The American Bladdernut expanded in early May, the Staphylea trifolia being the most plant produces an abundance prominent. of perfect, greenish white, half Usually thought of as a inch long, bell-shaped flowers shrub to 10’ tall, American Bladder- borne on 2” long panicles. nut can be grown as a small tree Heavy flowering provides a attaining heights of over 15’. The nice contrast of white on national champion is a goliath green. Soon after, the flowers standing 36’ tall with an equal develop into the inflated capcrown spread. Perhaps more sursules or bladders from which prising is the fact that this champ is the name is derived. The 3growing in Macomb County, Maine. lobed, greenish white capsules are 1-1½ inches long and remind people of Chinese lanterns in midsummer. By August the maturing capsule starts turning brown as the small brown seeds also mature. The capsules often persist through the winter if squirrels and deer leave them alone. At this point, they make effective rattles. The bark on the older stems is attractive with
its linear white fissures against a greenish gray background. Culturally, Staphylea can be grown as a small tree – single or multiple stem, or as a large shrub. The plants are capable of colonizing by producing suckers and one plant on the University of Minnesota St. Paul campus has made a very nice mass planting to fill in a corner area. Like most plants, Staphylea does well in full sunlight but it is surprisingly tolerant of shade as well. I have seen it growing in very dense shade in the Vermillion river bottom in Hastings where it was too dark to take a picture. With too much shade a concern of many gardeners, Staphylea could be used more. As far as soil preferences go, it prefers moist, well-drained soils but seems to get along fine on most sites. A poorly drained, wet, clay-based soil would not bode well, and I suspect that is what eventually laid low our specimen in the Arboretum’s small tree collection where heavy clay soils abound. Soil pH does not seem to be a factor unless high pH is encountered. American Bladdernut will never become a standard household word in the horticulture world of woody landscape design, but it is an interesting plant that can certainly help enhance many landscapes. The outstanding visual aspects are the dark green foliage and interesting bark patterns. The curious aspect certainly would be the fruiting capsules or Bladdernut fruit structures. The shade tolerance is a definite asset to shady gardens. Perhaps best of all to some people is the fact that it is native. So be patriotic, plant American – Bladdernut that is!
TCA Award Winners and Graduates Volunteer Hours Contributed As of February 1, 2002 Bronze Level 100-199 hours Michael Sowers Jane Klein Anna Barker Gary Schneider Doris Carroll Sharon Fisk Ronald Reeves Margaret Kirchner Andy Sobert Terri Goodfellow-Hayer Dorothy Pederson Gordon Hanson Jackie Overom Lee Gilligan Barb Kirkpatrick Pat Friedrichs Paul Couture Vera Wagner Marilyn McKay James Zastera Barbara Stendhal Frances Eberlein Gail Griffin Harol Batzer Barbara Leschisin Paula Denman
Silver Level 200-299 Joyce Nellis Charles Hueser Audrey Dolby Diana Bolander Tim Wedekind Glen Hamleton Leah Peterson Nancy Bjerke Bruce Granos Gold 300-499 Warren Banks Cliff Johnson Sherry Atkins Gordon Herbst Mimi Hottinger Janet Larson Platinum Level Over 500 Lorrie Stromme Patti Lee Gates Carolyn Dingfelder Robert Condon Skip Rither Esther Filson Rita Nystrom Jim Nelson
Volunteer Opportunity
New Faces Amongst Tree Care Advisors As of April 20, the Tree Care Advisor program welcomed a new group of TCAs, fresh from the St. Paul training sessions. And as usual, they are a stellar group of individuals, representing some new counties, and strengthening the numbers in our traditionally strong counties. Please welcome these new members to our group: Polly Auguston, Monticello, MN pauguston@aol.com Stephanie Brody, Minneapolis, MN stephbr@earthlink.net Donna Enfield, Oak Grove, MN Peggy Fairbourne, Plymouth, MN peggy.fairbourne@juno.com Lynda Forbes, Brooklyn Park, MN kirbie1@msn.com Marie Freed, Sartel, MN m-jfreed@msn.com Jody Gerlach, Elk River, MN Dave Hanson, Coon Rapids, MN dlhanson@umn.edu Heide Ludwig, Buffalo, MN rosebud@spacestar.net John Muelken, Prior Lake, MN mojomuelken@aol.com Cindy Ralls, Minneapolis, MN ralls@williams-exec.com
Help Needed with Community Tree Program Survey
Sherri Roberts, Zimmerman, MN dlroberts@sherbtel.net
Help is needed with entering results from a survey recently sent to 854 Minne-
Dianne Rodenberg, New Ulm, MN ranger@newulmtel.net
sota Communities. The 8-page survey is being entered in Microsoft Access 2000. May be possible to accommodate other database software. Please contact Rich Hauer at work 651-296-0592 or at home 763-561-6935 if interested in assisting. Any level of interest or assistance would be helpful. The survey is a cooperative effort among the Departments of Natural Resources and Agriculture, Minnesota Shade Tree Advisory Committee, US Forest Service, and University of Minnesota.
Lu Schmidtke, Inver Grove Heights, MN lu.schmidtke@state.mn.us Kim Sullivan, Lino Lakes, MN sullivan_kim_@hotmail.com Susan Tracy, Bloomington, MN
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Printable Letter and Local* Boy Makes Good From Vera Wagner: Hi Gary,
Dave Hanson a.k.a. “The New Guy�
(*As it would likely appear in the newspaper in Guckeen, MN)
As many of you are already aware, there's a new face in the College of Thank you for the slides, and Natural Resources, and he's going I was able to fill in the blanks to become your new best friend! from the MSHS library (for her After a lengthy, national search, workshop). David (prefers Dave) Hanson was hired as the Research Specialist in Egan Parks and Recreation, Urban and Community Forestry on specifically Cathy Boluc, was April 15. As part of his responsibiligreat to work with. They made ties in this position, he will be ascopies of all the handouts withsuming many of the daily operations out any fuss and their janitor of the Tree Care Advisor program, helped me with set up and clean up. including the production of this My Master Gardener intern assisted newsletter, some of the training, with attendance and distribution of record keeping and web site eninformation. hancement. I think it went pretty well - I always A long-time resident of Coon Rapforget to mention something. One ids, Dave has a B.S. degree in comphoto (re: enclosed some photos of the workshop) is from the class - these puter science and mathematics from Mankato State University, and a B.S. were the die-hards with more questions after dismissal. We had 30 signed degree in natural resources with a concentration in forestry from the up and 2 walk-ins. University of Minnesota. As a reThe second photo is the Arbor Day turning, "time-for-a-change-intree planting at marsh Creek Park in professions" student in the College Woodbury. It was a miserable day, but of Natural Resources, Dave gained we got all 16 trees planted (the RIGHT some valuable experience in instrucWAY) and mulched. It was fun to tion when he served as a teaching work with a small group. They were assistant for the dendrology course. amazed to learn about planting depth Now at least one of us can identify and really got into checking the roots the plants we recommend. (ed. Note: be still my beating heart!). His teaching experience hasn't been Of the 34 people signed up, this is limited to tree stuff, though. Dave who actually showed up. The Boy has also been an instructor of First Scouts wimped out on us. I am orgaAid and C.P.R., was a certified EMT, nizing a program again for the Washand still maintains the First Reington County Horticulture Society. sponder Level. Dave Paulson and Cindy Matiski have agreed to do one table utilizing your But most importantly, Dave is an specimens. The scheduled date is Anoka County Master Gardener Monday, June 3. Please let me know a and a new Tree Care Advisor! So, good time to come by for them. Once you have a "brother" at the big desk again, I promise to guard them (the in Green Hall now and someone specimens) with my life (she always that shares a lot of common experidoes). Look forward to hearing from ences with you. you soon. Dave has definitely taken a circuiVera Wagner tous route to this point in his professional life. He was a senior software engineer for UNISYS in Roseville Minnesota, a challenging position that he enjoyed with a company that he spent 18 years with. However, his love of the outdoors, camping in the Boundary Waters and gardening was always in the back of his mind. Fortunately, when he decided to follow his heart, he stumbled across the University of Minnesota, in particular the St. Paul
campus and the College of Natural Resources. It met all of his criteria for returning to school: convenient to his home in Coon Rapids, nationally recognized program, and it was on a smaller, more friendly campus. We lucked out! After Dave graduated from the U, he was able to garner one of the coveted urban forestry internships with the City of St. Paul. This short-term internship evolved into a full-time, urban forestry internship and exposed Dave to just about every aspect of urban forestry that a larger, metropolitan area could offer. Dave gained valuable experience in disease inspections, community relations, and created a G.I.S. layer of all 2183 trees in St. Paul that are "growing" in sidewalk tree grates. He also worked on their street tree inventories, conducted public forums on prescribed burnings (in regards to forestry operations) and invasive species, and honed his Power Point presentation skills. Dave and his spouse Patti have two children; one, a junior at Winona State University and the second is a sophomore at Coon Rapids High School. Dave lives the volunteer spirit, too, and is an active volunteer in several other school and church activities. In addition to doing a lot of the TCA program management, Dave will also be working on several urban forestry research projects jointly conducted by the departments of horticulture and forest resources - writing of urban forestry articles, and co-presentations at various workshops and conferences. Personally, I don't think we could have found a better person for the job. Dave is a very easy-going person, a good listener, and very willing to learn and take on new projects and responsibilities. His office is on the second floor of Green Hall, St. Paul campus, north end of the hallway. If you need help or just want to introduce yourself, stop by and visit with Dave. I know you'll be as impressed with him as I have been.
Native Species Not Always Best Choice When Planting
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Katie Frerker
temperatures, soil types, and moisture regimes throughout the state. Just because a plant is native to Minnesota does not mean Often times when people set out it is native to the area that you to plan their landscapes, the first live in. Before purchasing a tree question they ask is, “What spe- or shrub, check to make sure it can survive in the site you wish cies should I plant?” A recent to plant it. trend in landscape planning has been to plant native species. While planting native trees and shrubs have a number of different Just Because It’s In Minnesota Doesn’t Mean It’s Minbenefits, there are a number of different conditions under which nesotan these species can actually be Once you have determined more endemic than a foreign whether or not the species you plant species. wish to plant is native to your area of the state, you must then A plant native to Minnesota can be defined as belonging to a local- look more specifically at the site you wish to plant it on. Plants ity or country by birth, producnative to the state of Minnesota tion, or growth, that is, indigenous. “As found in nature, natu- are not necessarily native to the urban alterations to the landral and not refined, adorned or scape that have taken place for altered by man (www.dnr.state.mn.us/backyard/ years across the state. You must landscape/native_plants).” While ask yourself a few critical questions before deciding upon a spethere are a number of different benefits associated with planting cies to determine whether or not native species on your landscape, it can survive on an urban landmany of them are very dependent scape: How tolerant is the speupon the site conditions and may cies to smog in the city? How actually be a worse choice than a resistant is the species to decay once it has been wounded? How non-native tree or shrub. The shade tolerant/intolerant is the following are a number of cases species? Is there enough growing where planting a native tree or space on my landscape for this shrub species may not be the type of species? Will other plant best option for your landscape. species on my site compete with this species and inhibit its survival? Has the soil composition Where In Minnesota Is The on my site been altered over Species From? Many times people choose native time to no longer suit this type of plant species? Often times the species because they feel native answers to these questions may plants are best adapted to the local climate and once established require the expertise of a more qualified individual. There are a rarely need watering, mulching, number of different companies in mowing, or protection from frost. This may be true in some the metro area that will form cases, however, not in all. Many plant health care management plants that are native to the state plans for your site who will take all of these questions into considare native only to certain areas and plant communities. A tree or eration. You can find a list of different arborists who specialize shrub that thrives in northern in tree and shrub planting by visitMinnesota may not make it through the first year if planted in ing the Minnesota Society of Arboriculture’s website at http:// the southern part of the state. www.isa-mas.org/ and following Minnesota has a wide range of the “Certified Arborists” link. University of Minnesota
Do A Background Check First! Many times, when buying native seeds or seedlings, the supplier may dig them up from the wild. This can be very problematic for several reasons. Digging up plants from the wild can disrupt precious plant communities in Minnesota. If the plants are harvested from a native prairie community, repeated collections may have a negative impact on plant populations. Bouteloua gracilis Also, there is a potential for plants dug from the wild to be Photo courtesy of Paul Jackson on the state endangered, Cedar Creek Natural History threatened, or special concern Area species list. It is illegal for a supplier to sell or purchase endangered or threatened plant species. It is also ethically questionable to sell or purchase species of special concern. If you are going to purchase native plants, be sure to check the background of the supplier and make sure they have been legally salvaged with proper permits. Planting trees and shrubs native to Minnesota can be beneficial for many reasons; however, one must use caution when deciding what species to plant on his or her landscape. For more information on native plant species, check out the Minnesota Native Plant Society’s web page at http:// www.stolaf.edu/depts/biology/ mnps/. Or, if you live in the Twin Cities metro area, the DNR website (http:// www.dnr.state.mn.us/backyard/ Cypripedium Canadensis landscape/native_plants.html) Photo courtesy of Paul Jackson has lists of several different Cedar Creek Natural History species that are native to the area. Just follow the Area “Landscape Design With Native Plants” link. It is important to remember, however, to make sure the species is also compatible with the conditions of your specific site before making your final decision.
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Myth Number 1: Arboriculture Myth Exposed! By: Andrej Peterka Graduate Student University of Minnesota
first set of branches. In terms of physics, this displaces the forces driving natural swaying in wind to a very small area, often resulting in breakage at the stabilization Attorney General John point. Try firmly holding a drinkAshcroft recently expanded the ing straw half-way up its length, war on domestic terrorism to then wiggle the top back and include the staking of newly forth to better understand this planted trees, stating: “Any act against trees, one of our greatest concept. national resources, is an act In reality, young trees need to against America itself. We will sway. An impressive sounding stop at nothing short of arborial phenomenon (thigmotactic retribunals to end this barbaric, sponse) occurs when trees sway. unjust and unfounded oppression The swaying itself causes trunk of our woody innocents. God diameter to increase more bless trees and America!” quickly than if the tree is immobiWhile the above statement falls in the “less than true” category, there are those (arborists, trees themselves) who might wish it had indeed been made. Staking newly-planted trees is an often unnecessary, often damaging yet frequently observed practice. Like urban myths, no one is quite sure who started the idea, but it is firmly embedded in public consciousness. Fear of trees blowing over is the driving force behind staking trees. In the case of spindly remnant trees in new developments snapping or blowing over, this may actually have been observed. Containerized trees are often staked in nurseries, and architectural specifications will often call out staking in planting plans. The Joneses down the street, a formidable force in the suburban consciousness, have their trees staked. With all of these “experts” calling for the practice, it must be the thing to do, right? Wrong! There is no research supporting the practice of tree staking. In fact, recent research at the University of Minnesota shows just the opposite: staking newly planted trees often leads to their decline and failure. How is this so? When trees are staked, stays are often fastened below the
It’s what we’ll call “stakeulation.” Trees conduct most of their water and nutrients just under their bark in an area called the cambium. Prolonged pressure on the tissue, which increases as the tree’s diameter increases with growth, cuts off the flow and strangles the tree.
Remember the politically incorrect “Indian burns” of your youth? Think about doing that for three or four years, and you get an idea of another hazard of tree staking. Movement of the tree’s trunk with wind can create rubbing damage from the stays lized. This trunk thickening alabrading the tree bark. Young lows trees to stand on their own, trees generally have thin bark and staking will actually inhibit that is easily damaged this way. this process, leading to trunk Again, abrading the bark away breakage (What we were trying damages the cambium just beto avoid in the first place!) once neath it, causing stress or death stakes are removed. Natural from lack of water and nutrients. swaying also encourages the for- It also provides sites for insects mation of stabilizing root and or diseases to enter the trunk. proper trunk taper, which is These are just a few of the wider at the bottom than near reasons not to stake newly the branches. Look at any older, planted trees. To find others, established tree to get an idea of check out your local university’s what this looks like. extension website or websites Here’s an experiment that like: www.ucdavis.edu, demonstrates another hazard of www.cfr.washington, ohioline.osu.edu… Do a search on tree staking. Have a friend (or these sites for “tree staking.” better yet, an enemy) stand diYou can also use a general Interrectly in front of you. Take a net search engine like Google or necktie and gently but firmly Yahoo and search under “tree tighten it a wee bit too much staking” as well. You’ll find around the subject’s neck for a plenty of sites that explain the period of a few years while you hold the loose end taut with your perils of staking. hand. During this time, have So when should you stake, if them frequently move their head ever? Dr. Linda Chalker-Scott, in all directions. Note the rean associate professor at the Unisults, especially during mealtimes versity of Washington, recomand breathing. mends staking for bare root trees until their roots become established. You can check this by gently pulling up on the trunk after the tree has been planted for a few months. If it doesn’t pull up, the roots have established themselves and you can remove the stakes.
Wire girdling a stem.
Continued on page 16
Page 15
Myth Number 2: Bigger is Better? By: Jonah Reyes B.S. in Horticulture, University of Minnesota
After working in the landscaping installation business for the past three years, a common question homeowners ask regarding plant material is “What is the biggest size I can get?” In their minds they are envisioning an “insta-scape” with lush, flowering, fully-mature plants. Little do they know they are really asking “How can I lower the chances of my plants surviving for more money?” The purpose of this paper is to prove why bigger plants are not always better. Trees, like humans are most vigorous when they are young. The largest amounts of growth are experienced during the first stages of their life. Fastgrowing trees can grow five feet per year vertically and have as much as three feet of root growth per year. According to a website from the Galveston County Extension agency, growers define a large tree as having a trunk diameter of two inches or larger and a medium-sized tree as having a trunk diameter of one to two inches. In order to maintain the large amounts of crown area, a tree must have comparable amounts root mass to translocate water to the rest of the tree. If the ratio of root mass to crown area is disrupted during the transplanting process then the tree experiences transplant shock.
People wonder why their trees look ‘sick’ even though they are watered and fertilized frequently after transplanting. Trees that are transplanted with a tree spade usually experience a ninety-five to ninety eight percent root loss, depending on nursery practices. The majority of the roots that are lost are fine roots which are responsible for the majority of the water uptake for the tree. A nursery practice that can increase the percentage of fine roots in a root ball is called root pruning. Root pruning initiates fine roots from the callus tissue formed at the site of wounding. However timing of root pruning must be taken into account in order to take advantage of the root regeneration. It is recommended that root pruning be performed between the second and fifth years before the tree will be harvested. If root pruning is done too early, one dominant root will develop and the remainder of the fine roots will die. Research with green ash and Norway maple trees has shown that root initiation from a large (1 inch or more) severed root is reduced compared to initiation from a small (less than 1 inch) severed root. This reduction in root regeneration will cause water stress during the first and second growing seasons following transplanting.
A healthy crown will be conducive to the success of the transplanted tree. The crown is made up of foliage, trunk and branches. The foliage is both beneficial and detrimental at the same time. Leaves are responsible for producing carbohydrates which are used by the tree and in Transplant shock, simply stated is root the case of a newly transplanted tree, the loss. Trees respond to root loss by slow- roots. Leaves are also responsible for ing down processes which are not a netranspiration which is the loss of water to cessity to survive. This may include rethe atmosphere. Smaller trees have less duced flowering, abnormal leaf growth, crown area and therefore pose less of a and reduced processes related to photo- threat for added stress. synthesis such as transpiration and respiration. They also withdraw nutrient and water supplies to any ‘dead weight’ such The following is a comparison of root and as excess foliage or weak branches which crown growth between one inch and four eventually die. Symptoms related to these inch caliper trees following transplanting. stresses include abnormal leaf drop, pre- It was extracted from the Clemson Extenmature leaf coloring and overall tree desion website of a forestry leaflet written cline. Therefore the larger the tree at the by Donald L. Ham and Larry R. Nelson, time of transplanting, the more difficult 1998. and longer it will be for the tree to recover from the loss of root tissue.
Root and Top Growth of a OneInch Caliper Tree Following Transplanting A 1" caliper tree would have a root diameter of 4.5 feet. By nursery standards a root ball of about 1.5 feet would be moved. Less than 5% of the root system is transplanted. First Year.
The tree is under severe water stress soon after transplanting. With good care the stress diminishes, and the root system diameter should increase to 4.5 feet, 100% of the original, by the end of the first year. Roots and top are now balanced and the tree should grow with normal vigor.
Root and Top Growth of a FourInch Caliper Tree Following Transplanting A 4" caliper tree would have a root diameter of 18 feet. A root ball of 3.5 feet would be moved. Less than 5% of the root system is transplanted in the root ball. First Year.
Root system diameter increases to 6 feet, 9% of original volume. With less than 10% of the absorbing roots to support a full crown (top), the tree is often under severe water stress, inhibiting top growth, including bud formation.
Page 16 Second Year. Myth: continued from page 14
Some tree species like bicolor oaks have floppy trunks as juveniles so staking will be necessary for a while no matter what. Similarly, if the tree has an unstable stem for some reason, you’ll have to stake it until it stabilizes.
Root system increases to 9 feet, 23% of original volume. The tree remains frequently under water stress, inhibiting current season growth.
Third Year.
Root system diameter increases to 12 feet, 41% of original volume. As root/ top balance is gradually restored, the tree is exposed to less water stress and growth improves. Fourth Year.
Trees are a complex living system that perform under the worst possible conditions yet are continually expected by homeowners to provide their matchbook homes, built in a nutrient depleted landscape, with everlasting color. As hard as it may seem to endure the maturation process of a young tree, the benefits in the long run will be rewarding. Trees add value to any landscape and it depends on their care and management how long that value will last.
Harris, R.W., J.R. Clark, N. P. Matheny. 1999. Arboriculture Integrated Management of Landscape Trees, Shrubs, and Vines. Prentice Hall, New Jersey.
Fifth Year. Root system diameter increases to 18 feet, 100% of original volume. Roots and crown and the tree should grow with normal vigor.
When staking, don’t secure the tree too tightly. Allow some room for the tree to sway. This will hasten trunk growth and proper root formation and minimizes breakage in high winds.
If your tree has been staked, remove them after a few months. Don’t leave them up for more than a growing season. Two or three months is plenty of time for References & More Information Clemson Extension webpage, 1998. http:// the tree to establish enough root and trunk support, and if you keep the stakes www.clemson.edu/extfor/publications/ in place beyond this, you may be “killing forlf17/ with kindness.” Galveston County Extension webpage, 2002. http://aggie-horticulture.tamu.edu/ galveston/index.htm
Root system diameter increases to 15 feet, 60% of original volume. The effective rate of root generation accelerates as the overall diameter of the root system increases.
If you do stake, place the stakes as low as possible on the trunk to control sway. Don’t go higher than 2/3 of the height of the tree. Often, the tendency is to secure the tree above the first set of branches. If they are above 2/3 the height of the tree, resist the temptation: you’re setting the tree up for trunk weakness and possible breakage, as I’ve outlined earlier.
If you have additional questions about tree staking, consult your local university extension service. If none exist in your area, try a reputable nursery or tree care service. They should be able to give you the information you need to make the best choice about tree staking.
Watson, G.W. 1986. Cultural practices can influence root development for better transplanting success. J. Environ. Hort. 4:32-34. Watson, G.W., E.B. Himelick. 1983. Root regeneration of shade trees following transplanting. J. Environ. Hort. 1:52-54.
Nylon tie left on too long.
Myth Number 3 and 4: Soil Compaction: What Can You Do? Article adapted from: “Soil Compaction: What Can You Do?” Original article authored by Jodi Dejong-Hughes. Regional Extension Educator West Central Research and Outreach Center 320-589-1711
Two Myths: While we are on the topic of myths, here are two more brought to light by Jodi Dejong-Hughes: 1.) Freeze-thaw cycles will alleviate a majority of soil compaction created by machinery, and 2.) What compaction "Mother Nature" does not take care of, deep tillage or sub-soiling will alleviate.
Over time, repeated freeze-thaw cycles will alleviate compaction. This happens quicker at the surface (top 2-5 inches) which may go through multiple cycles in a season; however, beneath that the ground typically remains frozen or not throughout the winter.
Vehicles used around construction sites are increasing in size and weight. Increases in weight, especially per axel weight, relate directly to depth of compaction. Compaction of 2 feet or more is not uncommon with today’s vehicles being driven on wet soils. For all practical purposes breaking up compaction below 18 inches is not easily accomplished.
Compaction: What is it? Compaction of soil is more likely when water is present to acts as a lubricant allowing particles to slide past one another. Construction equipment and even lawn implements generate enough pressure to compress or damage soil structure. Jodi states, “Soil structure is important because it is the number one defense the soil has against compaction and it determines the ability of a soil to hold and conduct water, nutrients, and air necessary for plant root activity.”
Figure 1: Illustration depicting compacted soils with reduced pore space for water and oxygen. It is almost a guarantee that soils on urban planting sites are compacted to some degree. Construction activities inadvertently and purposefully alter soil structure and composition.
For example: construction specifications typically call for compaction of soils to support building sites, roads,
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Page 18 sidewalks and other structures. Compaction for support generally extends well below and to the sides of the structure being built. Some typical specifications, dependent on soil types, call for compaction of soil within 5 to 10 feet of building sites and within five feet of roads. Also, expect compaction around backfilled utility trenches, driveways, construction material storage areas, graded sites and anywhere else that construction vehicles were driven on the job site.
Besides intentional compaction for structural support, tire traffic on a construction site is a cause of compaction. Vehicles generate compaction on two levels: compaction at the surface (6-8 inches down) and compaction as deep as three feet beneath the surface. While surface compaction is directly related to tire pressure of the vehicles in use, deep compaction is related to the per axel weight.
Construction Season: What can be done? For existing trees, the best medicine is prevention. A physical barrier protecting critical root zones for each tree or tree group is necessary. Calculating the critical or protected root zone (PRZ) is quite simple: measure the DBH (diameter at breast height or diameter at 4.5 feet off the ground) and multiply that measurement by 1 foot to 1.5 feet. Completely surround the tree with a protection barrier at the calculated distance from the tree.
Figure 2: Comparison of protected root zone (PRZ) estimations.
A: One common method used to define a tree's protected root zone (PRZ) is to consider it to be the part of the roots that lie directly below its branches within an area known as the dripline.
B: Approximate a tree's Protected Root Zone by calculating the critical root radius (crr). First, measure the tree diameter in inches at breast height (DBH). Then multiply that number by 1.5 or 1.0. Express the result in feet. dbh X 1.5 = crr for older, unhealthy, or sensitive species dbh X 1.0 = crr for younger, healthy, or tolerant species
Page 19 Compaction Happens: The Next Step - Vertical mulching or radial trenching: If the soil is compacted around the base of an existing tree, there is little that can be done to correct that compaction. Typical solutions include Roto-tilling or Roto-vating to depths of 13 inches. These solutions would result in substantial root loss to trees since the majority of a trees fine roots are in the surface compaction zone of 0-8 inches. To assist the tree in its recovery vertical mulching or radial trenching techniques are recommended. These techniques provide loose, aerated soil for root development. Small holes approximately 2-3 feet on center (2-3 inch diameter by 8-12 inches deep) or narrow trenches (6-12 inches wide by 8-12 inches deep) are created beginning about 3-8 feet from the base of the tree and continue around the tree. Care should be used to avoid the major support roots of the tree. Figure 3: Comparison of vertical mulching and radial trenching in the protected root zone (PRZ).
A: Vertical mulching consists of a series of 2-3 inch diameter holes spaced 1, 2, or 3 feet on center within the critical root radius or the protected root zone of the tree.
B: Radial Trenching consists of 3-5 trenches 6-12 inches wide by 8-12 inches deep starting at 3-4 feet from the tree and extending out to the edge of the critical root radius or protected root zone of the tree.
Again, soil compaction within the protected root zone of the tree will not be undone with these methods. Soil amendments such as sand, compost, peat, or a combination of these are used to fill in the vertical holes or radial trenches. Roots easily penetrate and develop in the amended non-compacted soil.
For the original article please see Website: DeJong-Hughes, Jodi. “Soil Compaction: What Can You Do?” May 2, 2002. Online. Internet. 5/21/2002. Available. http://www.plpa.agri.umn.edu/extension/news%20releases/mncn57.htm. For Additional information on Protecting Root Zones: Johnson, Gary R. “Protecting Trees from Construction Damage: A Homeowners Guide”, (1999): Online. Internet. 5/21/2002. Available. http://www.extension.umn.edu/distribution/housingandclothing/DK6135.html. For Additional information on vertical mulching and radial trenching: Johnson, Gary R. “Better Trees Through Better Soils or, Can You Compact Soils Without Compacting Trees?”, Online. Internet. 5/21/2002. Available. http://www.mntca.org/tcahtml/better/better.htm
Contact Phone Numbers Program Contacts:
Gary Johnson – 612-625-3765 or grjonson@.umn.edu Dave Hanson – 612-624-1226 or hanso355@umn.edu Mailing Address: 115 Green Hall, 1530 Cleveland Ave. North, St. Paul, MN 55108
TCAAG Members:
Paula Denman - 612-338-1871 Bob Condon - 952-890-1228 Mimi Hottinger - 507-388-4838 Barb Kirkpatrick - 651-490-9816 Bruce Granos - 952-423-5211 Lorrie Stromme - 612-788-5157
County Contacts:
Anoka County (Patrick Weicherding) – 763-755-1280 or weich002@umn.edu Blue Earth – (507)389-8325 Carver County - (952) 442-4946 Dakota County (Barb Stendhal) – 952-463-8002 or stend004@umn.edu Hennepin County (Bob Mugaas) – 612-374-8400 Olmstead County (Doug Courneya) – 507-285-8250 or courneya@umn.edu Ramsey County – (Doug Foulk) – 651-777-8156 St. Louis County (Bob Olen) – 218-726-7512
Additional Reference Contacts:
Debby Newman (Info-U) – currently 651-704-2069, After July 1st 612-624-3263 Don Mueller, DNR Forestry – 651-772-6148 or don.mueller@dnr.state.mn.us Great River Greening – 651-665-9500 Ken Holman, DNR Forestry – 651-772-7565 or ken.holman@dnr.state.mn.us Rich Hauer, Minnesota Department of Agriculture (certified tree inspector workshop coordinator) 651-296-0592 or rich.hauer@state.mn.us Paul Walvatne MNDOT – 651-284-3793 or Paul.Walvatne@dot.state.mn.us Tree Trust – 651-644-5800
Photo Credits: American Bladdernut (Staphylea trifolia), Red Osier Dogwood (Cornus sericea) photos: Courtesy of Virginia Polytechnic Institute and State University. “http://www.cnr.vt.edu/dendro/dendrology/main.htm”