��

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

Inside ThIs Issue2 Perspectives Column

3 Mystery Tree

6 MnsTAC Awards

7 Firewood Restrictions go into effect on DNR Administered Lands

11 Tree Care Advice for Dry Weather

14 Moving Water from the soil to the Leaves

15 Mnstac & Calendar

16 What’s happening With the Minnesota Tree Inspector Certification Program?

Visit MnSTAC on the Web at www.mnstac.org

Midwest Center continued on p. 4

COMMUNITY FOREST PROFILE

ADVOCATE • Summer 2007

Summer 2007

VOl. 9, NO. 3

Midwest Center for Urban and Community ForestryBy Jill Johnson

The Midwest Center for Urban and Community Forestry is an entity of the U.S. Forest Service devoted to improving urban forestry technology transfer in the seven Midwestern states (Minnesota, Illinois, Indiana, Wisconsin, Michigan,

Iowa, and Missouri). It brings together the expertise of Midwestern practitioners, educators, and scientists to integrate knowledge and work toward common goals.

How does the Center function?An advisory committee representing a broad range of urban forestry profes-sionals constructs a prioritized list of urban forestry issues in the Midwest. The Forest Service and advisory board then work together to identify projects that would best address these needs. In some years, project proposals are solicited from outside organizations, and in other years, ideas are developed by the group of advisors. The Forest Service ranks the projects according to importance and cost and makes final decisions about what will be completed each year.

Center activities are coordinated by one full-time staff member who either works internally to complete projects or administers grants and contracts to outside orga-nizations. Internal initiatives often utilize the expertise of other Forest Service staff—including urban foresters, entomologists, pathologists, wood utilization specialists, and communications teams.

When was the Center formed?The Center was created in 1992 under the leadership of Lisa Burban (Urban Forester) and John Dwyer (Project Leader for Forest Service Research). At that time, it was based in Chicago. The Center moved to St. Paul in 1998.

22

PERSPECTIVES COLUMN

Summer 2007 • ADVOCATE

By Jill Sinclair

Maybe it’s just me. Maybe it’s just my own issue of avoidance, but when someone asks me the question, “So,

what do you do?” I start to cringe. It’s not because I’m not proud of what I do or love what I do, it’s because the scenario plays out nearly the same way every time. I start my answer in general terms. “I work for a city.” “Oh, doing what?” “I’m an Environmental Resources Specialist.” And then, bam, there it is. The thing I dread. The blank stare. In this day and age, when janitors and garbage haulers work in Environmental Resources,

and manufacturing, engineer-ing and landscaping jobs are all listed in the want ads under Environmental Positions, it’s easy to see why there is no recogni-tion of what kind of job I might actually be doing. At that point, I quickly backtrack and say, “I’m a forester.” Whew, they can picture Smokey Bear and green polyester pants. Not at all close to what I do, but at least there’s an image.

So why am I called an Environmental Resources Specialist and not a City Forester? Good question. I think the different titles reflect a slightly different set of responsibilities. Forestry is still at the heart of what I do, but the body

of my work also encompasses development plan review, environmental education, commu-nity gardens, habitat restoration, recycling education, and city environmental events. I also have to know just enough about wildlife, alter-native energy and sustainability to cover any environmental issue that makes its way to city hall. In this day and age of multi-tasking and having to do more with less, Environmental

Resources Specialists seem to make sense for a city. They get an employee who can manage trees, land, and everything in between.

There are times when I worry that the important forestry work that needs to be done is falling by the wayside because I’m preparing for a citywide recycling event or a garden tour. That’s when I begin to wonder if the shift towards general environmental positions comes at a price of the good, solid forestry program a city needs. But I think the bottom line is that the quality of work depends on the person in the position and the vision of the community. Forestry will always have a place in cities that value their trees. Whether the responsibility falls to a City Forester or an Environmental Resources Specialist shouldn’t make a difference.

We urban foresters tend to be generalists anyway. We can’t help but know a little (or a lot) about horticulture, entomology, soils, wildlife, and pathology. We have the ability to cover a wide range of topics and issues within the scope of our work. I think that’s what makes the job so interesting. You’re not buttonholed into repetitive work. No day is ever the same, although there are crazy times when I dream about how nice it would be just to push papers all day. But then I would miss the call like I got yesterday: “Can you come and get a hornet’s nest out of my shrub? My neighbor told me you would do that.”

Jill Sinclair is an Environmental Resources Specialist with the City of Chanhassen. She can be reached at 952-227-1133.

Forestry will

always have a

place in cities that

value their trees.

So you call yourself a forester?

Answer on page 14

ADVOCATE • Summer 2007 3

?

This tree is native to the southern half of Minnesota. It is a full sized, long lived, fast growing tree.

Full sun is best but it will take some shade. With nice yellow leaves in the fall, this tree is a great addition to any yard. It is also a good tree on a boule-vard, but not where you might expect a lot of salt spray from passing traffic.

The leaves are asymmetrical and prone to a lot of nipple gall. The nipple gall is not a problem for the tree. The bark is fabulous and unique, with lots of corky ridges on medium sized trees. The tree is good for wildlife and has small dark purple berry-like fruit. It was often thought to be a good replacement for the American elm, which is not surprising, since both are related.

Mystery Tree...

Photos: Robert Slater

Summer 2007 • ADVOCATE�

What types of activities are considered “technology transfer”?

• Packaging technical information in a way that is useful

• Encouraging the use of research and innovation for managing urban forests

• Sharing innovative projects that are being completed in other states and regions

• Addressing “Hot Topics” (of broad concern and timely in nature)

• Developing streamlined systems for making information available to a broad spectrum of audiences

What are some examples of the Center’s initiatives?Current Projects

• Tree Owner’s Manual (being developed internally)

One common issue facing Midwesterners is the fact that trees are dying prematurely because they are planted improperly and not maintained over time. To help remedy this issue, the Center is creating a Tree Owner’s Manual—science-based information in a user-friendly format.

Just like the owner’s manual that comes with automobiles and appliances, this booklet includes a parts list, instructions for installation, troubleshooting common issues, recommended service (how to hire an arborist), and more. Cautions for safety and quality assurance are also included.

The Tree Owner’s Manual will be inexpensive to reproduce so that it can be made widely available to garden centers, nurseries, landscapers, and arborists to hand out to customers. And like other owner’s manuals, hopefully it will be kept in a familiar spot and used as a reference over the course of the tree’s life.

• Before the Bug Comes to Town (being developed internally)

All Midwestern states are in the line of fire of the emerald ash borer. Even those states that

have an infestation still have unaffected communities that are trying to prepare. To help communities get ready, the Center is developing a booklet that contains a prioritized list of activities to complete in advance of an infestation and tips for carrying them out inexpensively.

• Electronic Tree Risk Assessment Calculator (cooperative project)

The Center is testing the beta version of this software program designed for use on Personal Digital Assistants. The program is a companion to the Forest Service publication, “Urban Tree Risk Management: A Community Guide for Program Planning and Implementation.”

• Distribution Plans for Completed Projects (being completed internally)

A large part of the Center’s role in these projects is in developing distribution strategies so that the oftentimes limited supply gets into the hands of those who will benefit the most.

• What Works? (being completed internally) To gauge the success of outreach efforts and

determine what types of media are most effective for various audiences, the Center will be conducting follow-up evaluations of recent projects.

Recently Completed Projects• Stem Girdling Roots:

The Underground Epidemic Killing Our Trees (grant to the University of Minnesota)

“A Practitioner’s Guide to Stem Girdling Roots” (a 1997 Center project) has been extremely successful at teaching professionals about dysfunctional roots. But it became apparent that this same information needed to be communicated to homeowners. Therefore the Forest Service provided funds to the University of Minnesota to create this photo-rich booklet describing the problems with stem girdling roots, prevention, diagnosis, and treatment in a language and style appropriate for anyone.

Midwest Center continued from p. �

Photos by Deb Rose, MN-DNR

ADVOCATE • Summer 2007 �

• Trees and Ice Storms 2nd Edition (grant to University of Wisconsin—Stevens Point and University of Illinois at Urbana‑ Champaign)

Trees in ice storms can result in downed utility lines, blocked roads, and damage to homes, but research shows that the extent of destruction can be minimized. This edition updates the 1994 publication with ten more years of data. It describes the impact of ice storms on trees and the consequent damage to other infrastructure. Most importantly, it provides practical suggestions for developing storm-resistant urban forests and tips for recovering.

• Anti‑topping Campaign (grant to Forest ReLeaf of Missouri ‑ completed)

Some Midwestern states are still battling the practice of tree topping. To meet this ongoing challenge, the Forest Service helped fund the development of anti-topping campaign materials, including a logo, posters, flyers, and letterhead. Materials were targeted toward women after a market survey identified the fact that it is usually the female member of the household that makes the decision to hire tree care services.

• Trees Pay Us Back Website (developed internally)

Recent research has provided information about the benefits of trees in the Midwest. To make this information accessible and provide a “one-stop shop” for all tree benefits research, the Center created a website called “Trees Pay Us Back.” The site links to existing research as well as tools (such as Power Point presentations and flyers) that highlight the value of city trees.

• Urban Forestry Index (cooperative effort with multiple partners)

This online database of urban forestry and arboriculture publications and other media can be searched by topic, author, geographic region, format, or keyword. After several years in development, the national database is now fully-functional and is currently being populated with Midwest materials. www.urbanforestryindex.net

• Seasonal Care Calendar Poster and Magnet (grant to the University of Minnesota)

The Forest Service partnered with the University of Minnesota to create a chart showing the optimal seasons for planting, pruning, and protecting woody plants. A poster was designed for golf course superintendents, park and recreation directors, public works directors, and other professionals outside of the arboricultural industry who are responsible for tree care. A smaller version, printed on a magnet, depicts less information, but is a convenient reminder to homeowners about basic tree care needs.

Midwest Center continued on p. 6

Photos by Deb Rose, MN-DNR

Summer 2007 • ADVOCATE�

Congratulations MnSTAC Award WinnersBernie AndersonOutstanding Volunteer of the Year Award for leadership in New Richland tree plantings and Tree Board contributions.

Fred Rozumalski and Barr Engineering VolunteersOutstanding Volunteer Project Award for Minnetonka Natural Resources Stewardship Program.

Representative Diane LoefflerStewardship Award for State Urban Forestry Policy in the Minnesota State Legislature.

Matt Stone2006 Outstanding Youth Project Award for Wadena’s Walking Tree Memorial Lane.

Tree Trust and Mayor R.T. RybakOutstanding Partnership Award for the Minneapolis City Trees Project.

Mayor R.T. RybakStewardship Award for Leadership and Commitment to Urban Forestry.

Spruce Up AustinOutstanding Arbor Day Award for the 150 Heritage Tree Project in Austin, Minnesota.

• Speakers Bureau (developed internally) In hopes of providing ideas to conference

organizers about potential topics and speakers, the Center recently assembled a list of presentations that have been given. The list is categorized by topic and provides titles, descriptions, and speaker names. This list will continue to grow as new conferences and workshops are held across the country.

• Train‑the‑Trainer Workshops (cooperative effort with multiple partners)

With the intent of producing a greater number of qualified trainers on key urban forestry topics, four train-the-trainer workshops were held throughout the Midwest. The subjects included urban tree risk management, storm preparedness and response, technology for urban forest management, and inventorying community trees.

• Webcasts (completed internally) The Center helps government, non-profit,

and higher education organizations host

Jill Johnson is the Coordinator of the Midwest

Center for Urban & Community

Forestry.

Midwest Center continued from p. �webinars and webcasts if they do not have the necessary software or expertise in-house. The Center also utilizes webcast technology to promote Center projects nationally.

• Presentations (completed internally) The Center Coordinator gives presentations

on hot topics and cutting edge technologies. Examples include: t i-Tree (new software that helps inventory

urban forests and assess costs and benefits)t PDAs for urban forest inventory and

managementt Resources for a Green Community (75 of

the hottest informational products—publications, websites, DVDs, software)

tPreparing for the Emerald Ash Borer (community readiness)

To find out more information or to download a copy of the above resources, visit the U.S. Forest Service website: www.na.fs.fed.us/urban/inforesources

ADVOCATE • Summer 2007 7

URBAN FOREST HEALTH

By Susan Burks

The Minnesota Department of Natural Resource’s (DNR) proposal to restrict all firewood entering DNR administered

lands to that which has been approved by the Commissioner was passed this spring by the state legislature and signed into law. In the new law, approved firewood includes wood sold by the DNR or obtained from an approved vendor. Campers needing to locate an approved vendor or vendors wanting to apply to be approved can do so by going to http://www.dnr.state.mn.us/firewood/index.html. Any vendor can apply as long as their wood comes from within Minnesota and from within 100 miles of the DNR facility where the wood will be used.

So why pick on firewood?Campfires are a critical part of the camping experience and the DNR has no desire to change that. Campfires are an important part of the culture of outdoor recreation and the DNR wants to keep it that way. But it is critical that campers recognize the risks they are taking by moving firewood from one area to area. Folks are putting the State’s forests at risk, as well as the trees that make our communities livable.

Just like other raw wood products, firewood can harbor invasive insects and disease pests. And just like other raw wood products, the movement of infested firewood can spread these pests to areas where we don’t want them. But unlike other raw wood products, firewood is moved primarily by home owners and campers who do not fall under state and federal regulations meant to limit accidental introductions of these bad bugs. So the point of this legislation is to change how we think about firewood and the precau-tions we take to protect the things we love.

What about the other guys?When a bad bug becomes established within a state, state and federal regulations are put in place to help keep it from spreading. So when the emerald ash borer (EAB) was found in Michigan, the state was quarantined. Quarantines do not ban trade, but they do regulate articles capable of harboring the pest. That means raw wood products and nursery stock have to meet certain criteria before they can be moved. In the case of firewood coming from EAB quarantined states, it means the bark has to be removed and the wood milled down 0.5” into the sapwood to make certain any EAB life stage has been removed. Or the wood has to be heat-treated for a set amount of time (based on the size of the piece) so that all EAB life stages are killed. Since either of these treatments would also kill a tree, ash nursery stock cannot be moved outside those states quarantined for EAB. Logs and other raw wood products have specific criteria for their shipment as well. So while there is always a chance for something to slip through, most commercially sold products are safe to move.

The exception may be firewood because of the nature of the industry. Anyone with a little land or a chain saw can go into business for himself or herself and many do. As a result, it is difficult if not impossible to keep tract of who is in busi-ness and make sure they are aware of state and federal regulations. And because small operators may or may not label their firewood bundles, it is difficult if not impossible to know where the wood is coming from. Even when the wood is labeled, you can’t be sure where the wood came from because the distributor listed on the label may be a broker half way across the country from where the wood was harvested.

“…firewood can harbor invasive insects and disease pests.

”

Firewood Restrictions Go Into Effect on DNR Administered Lands

Firewood Restrictions continued on p. 8

Summer 2007 • ADVOCATE�

Federal regulations do say that any firewood origi-nating in or passing through a quarantined area should display the federal shield on the pack-age label or invoice. The shield certifies that the wood has been treated to reduce the risk of it carrying a particular pest. But it’s important to note that carrying the federal shield does not mean federally certified firewood is better than non-certified firewood. To be certified, the fire-wood must come from or through an infested area. Since no control measure is 100% effective, certified firewood automatically has a higher risk of spreading a pest than firewood that comes from an area where the pest does not occur.

None of the regulated pests known to be associat-ed with the movement of firewood are established in Minnesota. So firewood produced in Minnesota is at no known risk of spreading those pests and therefore is not federally certified. Without the risk of spreading regulated pests, Minnesota wood is the safest firewood we can buy. So protect our forests and buy Minnesota grown firewood!!

So what bad bugs?Firewood can serve as a vehicle for a variety of forest insect and disease pests, including the fungi causing oak wilt and Dutch elm disease, wood stain fungi, gypsy moths, Sirex wood wasps, ambrosia beetles, bark beetles, and long-horned beetles. Although the movement of forest diseases and pests in firewood has been an ongoing concern, the approach of the emer-ald ash borer (EAB) has brought the issue to the forefront in Minnesota and nearby states.

EAB, a small metallic-green woodborer insect, poses an extreme threat to Minnesota’s ash tree population. First discovered in Michigan in 2002, EAB has spread to Indiana, Illinois, Ohio, Pennsylvania, Maryland and Ontario. Those areas are now all quarantined. Although not yet found in Wisconsin or Minnesota, EAB could easily spread to our state.

Infested trees are killed by the feeding activities of the EAB larvae, which bore through bark to feed on sapwood as they grow, creating serpen-tine tunnels while feeding. Adults bore exit holes in the bark, emerge in early June, mate, and lay the next generation of eggs in ash bark.

EAB are able to attack and kill both healthy and stressed trees. They also attack all species of ash, of all ages and forest types. Because they can kill trees outright without the assistance of stress factors like weather extremes or site disturbances, EAB is considered the number one threat to ash in the Great Lakes region.

What’s at risk?Minnesota has the third largest volume of rural ash in the country with over 1.2 billion cubic board ft. Our communities are estimated to hold another 3 million ash trees. This number reflects the fact that ash was the replacement tree of choice when Dutch elm disease took out a large number of our mature elms back in the 1970’s.

There are four species of ash found in Minnesota, although blue ash is of minor importance. Of the other three (black, green and white ash), black ash is the most abundant in rural Minnesota, and green ash is the most abundant in our communi-ties. Those folks here in the 1970s will remember the vast number of trees that came down due to Dutch elm disease and the large quantities of wood that piled up waiting for disposal. In reality, the outbreak that peaked in 1976 took out only about 50% of the mature elm in our urban areas. Since 1977 when the first commu-nity grants were awarded to help manage DED, losses have averaged between 3 and 10% annu-ally (2004 was an exception when the number of trees lost temporarily shot up again).

In comparison, the core area of EAB infestation in Detroit has lost close to 100% of their ash. During the first year after they discovered EAB in Michigan, the state hired 100 new employees and spent over $24 million in an attempt to contain its spread. And federal agencies spent even more. Since then, federal funds have been cut back and the state has given up trying to control the pest. That means that individual communities and their residents face the burden of removing large numbers of dead and dying trees without financial assistance. And estimates indicate that the rate of ash mortality is going up about 30% per year in the areas surrounding Detroit.

While communities face a huge financial burden, native populations face the possible loss of income

Firewood Restrictions continued from p. 7

9ADVOCATE • Summer 2007

and cultural pride. Black ash seems to be the most EAB preferred species of the ash. And the slower growing black ash trees, those best for basketry, are even more susceptible than their vigorous, rapidly growing neighbors. In the wettest native plant communities, black ash is found growing in monocultures. If the trees are lost, the water table is likely to rise, preventing new tress from becom-ing established. So if EAB is introduced into the state, those forests may be lost altogether. Less wet black ash sites will require careful management to maintain the water level at its current depth.

Why the DNR?The DNR manages 15% of the campgrounds in the state. So restrictions on DNR lands only address a fraction of the recreationally used fire-wood being moved around the state. And DNR restrictions wouldn’t touch firewood being used for home or cabin heating. So what do they hope to accomplish? While it’s a big undertak-ing, the DNR hopes to change public behavior with aggressive outreach and faith in Minnesota residents to do what’s right. So they plan to take every opportunity to educate campers. When they make reservations or check into their campsite for

the night, when camp hosts stop by for a chat or when folks go to buy their fishing permit, they will be seeing materials that explain the risks associ-ated with firewood and what to do to help protect their favorite campsite. So like Smokey Bear and the litterbug education campaigns of the 1950’s, the DNR hopes to use the proposed restrictions to gain public attention and convey the critical role resident’s play in protecting our natural resources.

The DNR also hopes to enlist the support of other landowners, so that recreationalists throughout the state get the same message. Toward that goal, the DNR has been hosting stakeholders meetings and talking to other public and private campground owners. As is already being done in Wisconsin, they are being encouraged to put similar restric-tions in place to protect their own resources. And as is being done in Wisconsin, the emphasis in Minnesota will be on education, not enforce-ment. Public outreach and the honor system will be the foundation of the DNR program.

What about MDA?The Minnesota Department of Agriculture (MDA) is the lead regulatory agency in invasive pest exclusion and management. As such, they have been key to coordinating the state’s effort. In February 2006, the Minnesota Department of Agriculture (MDA) organized an interagency fire-wood working group with representatives from the DNR, USDA Animal and Plant Health Inspection Service, USDA Forest Service, and the University of Minnesota. Each of these organizations has different authorities, different target audiences, and different concentrations of expertise. By coor-dinating their efforts, the group maximizes the chance of preventing the introduction of inva-sive pest species via firewood movement and provides an opportunity to accomplish a variety of objectives with minimal duplication of effort.

Education is the foundation of prevention. With that in mind, a sub-group was formed with addi-tional partners. Armed with the message not to move firewood; rather obtain your firewood at or near the site where you intend to use it, different partners produced a number of differ-ent educational pieces. These included letters, posters, bookmarks, surveys, highway billboards, presentations, workshops and several news media

Firewood Restrictions continued on p.10

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Summer 2007 • ADVOCATE�0

around the state. Targeted audiences include campground owners, firewood dealers, loggers & truckers, Minnesota Forest Resources Council, tourism and recreation organizations as well as the general public. Then in late April, the outreach effort was given a huge boost. Media attention given the passage of the new DNR firewood restrictions and the National Emerald Ash Borer Awareness Month came out just in time for the Memorial Day holiday weekend.

So what do I look for?Read the label and look for the place of harvest. Prior to this spring, the Minnesota Department of Commerce required all firewood sold in Minnesota to be labeled with its identity, quan-tity and distributor. However, the wood’s source or the place of harvest was not required on the label. Without that information, there is no way to determine what risk the firewood might pose for pest introduction. So an amendment was added to the legislation signed this spring adding to the labeling requirements. Effective August 1, 2007 firewood sold across state bound-aries, or more than 100 miles from its origin is also required to be labeled with the county and state from which the wood was harvested. For firewood sold in bulk, this information must be on the delivery ticket and for firewood sold in bundles or packages, this information must be on each label or wrapper. The requirement gives Minnesota producers a marketing edge that benefits producer and buyer alike, because buyers can now obtain firewood close to where it is grown, knowing they are protecting their forests.

Is that all we can we do?Because it is no longer possible to eliminate EAB from the United States, it will get to Minnesota eventually. But EAB only spreads a few miles per year on its own, so it could take decades to get to here, if not introduced. That potentially gives Minnesota a long time for research, plan-ning and forest management to limit future impacts. That makes it well worth the effort to keep EAB from being accidentally introduced.

What we can do is consider how our behavior impacts our natural resources. In particular, it is important to think about what we carry with us as we move from place to place and what in turn

may be on those articles. Just as aquatic plants can be spread on boats; bugs, disease agents and weed seeds can be spread on our belongings. With regard to invasive species, people are the biggest problem because new pest introductions are almost always associated with people. So when moving or traveling it is important to make sure our belongings are pest free. Think about where they have been and what could get on them. Inspect them carefully before moving them to another site. If you aren’t sure they are pest free, treat or thoroughly clean them or leave those belongings at home.

When camping or heating your home or cabin, you should

1) Use only wood that has been aged and/or dried. Aged firewood will often have bark that is loose or falling off. Besides burning more efficiently, aged firewood is unlikely to carry bad bugs because insects and disease agents can’t survive in dry wood.

2) Buy Minnesota grown firewood, 3) Buy your wood from a DNR approved

vendor or4) Check the label to make sure the wood has

been treated to kill all possible pests

Protect Our Forests Don’t Move Firewood

Susan Burks is a Forest Health Specialist with the Minnesota Department of

Natural Resources.

For more information on the DNR firewood regulations, visit http://www.dnr.state.mn.us/firewood/index.html.

For information on the MDA invasive species program, visit http://www.mda.state.mn.us/plants/pestmanagement/invasives.htm

To report a suspected invasive species, call the “Arrest the Pest Hotline” at 651-201-6684 or 1-888-545-6684.

ADVOCATE • Summer 2007 ��

By Patrick Weicherding

Recurring and prolonged periods of drought seem to have become commonplace in many regions of the country in recent years.

Even in Minnesota, viewed as a “water rich” state, drought is not all that unusual. Historical records and tree ring studies clearly show that drought is a normal, periodic feature of Minnesota’s climate. Despite the fact that it is normal and recurring, drought still causes significant problems with plant health, particularly to more permanent features of the landscape like trees and shrubs.

What is the impact of drought on trees and shrubs?Water stress affects most of the physiological processes involved in plant growth. The symptoms of drought injury to trees and shrubs may be sudden or may take several years to be noticeable. Initially, the leaves begin to wilt, followed by chlorosis (yellowing), browning and scorching. In conifers, there may be a noticeable yellowing and browning on needle tips.

During a prolonged drought, leaves may be smaller than normal, exhibit premature fall coloration or may drop prematurely. As the drought continues, there will be a reduction in photosynthesis followed by a reduction in root, shoot, height and diameter growth. Under continued drought conditions, plants suffer chronic stress and are very susceptible to opportunistic diseases and insect pest infestations. A severely stressed tree or shrub will be unable to defend itself against these secondary pests and will often die.

Tree care practices to avoid drought damageWhile no one can predict with certainty when a drought will occur or how long a particular drought will continue, we do know that droughts will occur periodically over time. Choosing the right plants for your location and caring for them properly are the best ways to lessen a drought’s long-term impact. Remember, drought damage can’t be fixed but it can be prevented.

Here are some drought-readiness tips:• Depending on air temperature and relative

humidity, which affect water loss through transpiration, most trees and shrubs need at least 1 to 1½ inches of water applied every week to 10 days to compensate for the lack of rain. Larger, established trees have a wide-spreading root system and probably don’t need to be watered as frequently, perhaps every 2 to 3

Tree Care Advice for Dry Weather

Tree Care Advice continued on p. 12

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Summer 2007 • ADVOCATE�2

weeks. Be sure to let the top few inches of soil dry out between waterings to avoid saturating the soil. Roots and soil organisms need oxygen as well as water in order to survive.

• It’s best to apply the water in one thorough, deep soaking. The soil should be moist to a depth of 8-12 inches. Frequent, light waterings only promote the growth of shallow roots that are easily damaged by drought conditions. Deep soakings encourage deeper root growth. You can check the soil moisture with a trowel or metal rod. With the trowel,

dig approximately 6-8 inches deep into the soil and use your hands to “feel” the moisture content of the soil. Or, with the metal rod check for ease of penetration—dry soils resist penetration.

• One of the most efficient methods of watering established trees is to use a soaker hose. This is an effective watering tool because it discharges an even stream of slow, trickling water directly to the root zone beneath trees and shrubs. Coil the hose around the tree base, out in a circular pattern. Start about 2-3 feet out from the trunk, and go out approximately 5 feet beyond the tree’s dripline—the imaginary line on the ground that encircles a tree’s extended branches. Water for several hours.

• An effective means of watering newly established trees is letting a hose run slowly at its base until the ground is moist. Build up a soil berm around the perimeter of the root ball. This will hold the water in while it percolates into the soil. Fill the basin with water and allow it to drain. Repeat until the rootball and soil are thoroughly moistened.

• If you have a large number of trees to hand water consider the use of a ‘Gator’ bag. A gator bag is a large plastic bag (often green in color) that can be used around the trunk of a newly planted tree or a younger tree as supplemental watering source in dry periods. They are basically plastic bladders that are placed around the tree, zipped up, and filled with water. The bag slowly releases water into the soil over about a two-day time period. The bags are easy to use, reusable, and effective at helping trees become established. Gator bags are often used by communities and park districts on trees in road medians or in demonstration gardens.

• Lawn sprinkler systems are a terribly inefficient way to water trees and shrubs. Too much water is lost to evaporation and what little does reach the ground is usually taken up by the turf. If you use a sprinkler system, place a container nearby to measure when you have distributed 1 inch of water to the soil.

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Gator bag for supplemental watering.

Construct a soil berm to keep moisture near the root ball on newly planted trees.

ADVOCATE • Summer 2007 �3

• Remember, plants vary in their ability to tolerate water stress. Prioritize watering, caring for newly transplanted trees and shrubs first, then those that have been in the ground from 2 to 5 years and have under-developed root systems. Next, water “specimen” trees or other important trees. Finally, water perennial flowers and grasses, annual plantings and, last but not least, turf grass. The reality is that turf grass is easily reestablished when the temperature cools and the rains return.

• Adding a 3-4 inch deep layer of mulch around trees will be very beneficial. Organic mulches are the best choice, as they will return nutrients back to the soil as they decompose. Mulch will help conserve soil moisture, cut down on weed and grass competition, and protect the stem from mechanical injury. Mulch the “critical root zone.” This zone should be at least as wide as the drip line of the tree and preferably 1.5 times the tree’s diameter in feet. For instance, a 4-inch diameter tree would receive a 6-foot ring of mulch. Keep the mulch a few inches away from the base of the trunk itself. Over-mulching or “volcano” mulching can promote decay fungi and stem girdling root development.

• Avoid using fertilizer during drought conditions. Fertilizer salts can cause root injury when soil moisture is limited. Fertilizers may also stimulate top growth resulting in too much leaf area on the plant for the root system to maintain during periods of limited soil moisture.

• Keep your trees healthy and pest free. Postpone construction activities planned near trees and shrubs to reduce impact to the plant’s roots. If your plants have any insect or disease problem that may be adding additional stress—treat them accordingly to reduce the overall stress to the plants.

• Properly prune trees and shrubs during time of drought to improve structure, limb stability and to remove dead and weakened branches. Leaving broken, dead, insect-infested or diseased branches can further weaken plants during drought and set them up for secondary insect and disease problems.

• Finally, remember that many trees and shrubs are harmed by broad-leaf herbicides used on the lawn. Plants already stressed by drought can be harmed by a heavy application of herbicide in the root zone.

Future OutlookThe future of your trees and shrubs will depend on their health and vigor prior to the drought and the severity of the drought at your particular location. Growing conditions vary by individual site and micro-climate so predicting future tree and shrub health on a broad scale is nearly impossible. Urban trees, recently disturbed or damaged trees, over-mature trees and those growing in sandy drought-prone soils are more at risk of mortality. In those cases, extra atten-tion to watering is critical to plant survival.

ReferencesCoder, Kim D. 1999. Drought Damage to Trees. Daniel B. Warnell School of Forest Resources, Extension Publication FR99-010, University of Georgia, Athens, GA

Douglas, Sharon. 2002. Minimizing the Long-term Effects of Drought on Trees and Shrubs. Connecticut Agricultural Experiment Station, New Haven, CT

Patrick Weicherding is a Regional Extension Educator and Professor with the University of Minnesota Extension Service.

Mulch around trees with 3-4 inches of organic mulch to reduce moisture loss. Pull back mulch 6 inches from the trunk of the tree

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Summer 2007 • ADVOCATE��

Moving Water from the Soil to the leaves

By Gary Johnson

For water to move from the soil to the roots, “available water” must be present. Available water is the amount of water in the soil between the two points of extremes. Field capacity is when the soil is completely moistened but not saturated. Permanent wilting point, as the name implies, is when the soil is so dry that no moisture can be extracted by plant roots.

Since water tends to move from areas of a high concentration of water to lower concentra-tions, thus begins the movement of water into plant roots. Roots have a higher solute (minerals and particles in the sap) concentration, therefore a lower percentage of water in their cells, so water will move “easily” from the soil into the root cells.

Most water is absorbed by root hairs and the small, fine roots of trees and shrubs. As water moves from the soil into the cells of root hairs or the fine roots, it eventually passes cell-by-cell through to the central vascular system (stele) of the root. This vascular system that begins in these tiny roots, less than four inches in length, eventually connects with the veins in the leaves of trees. As the roots take in more water and minerals, root pressure builds up and begins moving the fluids up the plant stem for a short distance.

Within the vascular system (xylem and phloem tissues), water is held tightly to the walls of the conducting tissues much like it hugs the inside walls of a straw in a drinking glass. Look closely at the water level in that straw and note that it not only hugs and moves up the insides of the straw, but the level of the water in the straw is a bit higher than the water level in the drinking glass. The same adhesion action observed in a drinking straw is found in the vascular tissues of a plant.

Finally, to get that water to rise to the uppermost leaf veins, it must be in the form of a continuous column of water. The cohesion-tension theory of water movement depends on a negative pressure (tension) developing due to the evaporation of water from a tree’s leaves. As water evaporates, the tension created pulls the now continuous column of water up the vascular system to replace the evaporated moisture.

Gary Johnson is a Professor of Urban and Community Forestry, Department of Forest Resources, University of Minnesota.

Mystery Tree Answer: The Mystery Tree is: Hackberry (Celtis occidentalis)

ADVOCATE • Summer 2007 ��

sTAC INFO & NeWs

Ecological Restoration. Andre F. Clewell and James Aronson. 2007. Island Press

Managing Growth in America’s Communities. Douglas R. Porter. 2007. Island Press

The Conservation Professional’s Guide to Working with People. Scott A. Bonar. 2007. Island Press

WebsitesAmerican Public Gardens

www.aabga.org

Alliance for Community Trees www.actrees.org

Hazard Trees http://na.fs.fed.us/fhp/hazard_tree

Human Dimensions of Urban Forestry www.cfr.washington.edu/research.envmind

Iowa Arborist Association www.forestry.iastate.edu/IAA/IAA.html

Minnesota Landscape Arboretum www.arboretum.umn.edu

Morton Arboretum www.mortonarb.org

Plants for People www.plants‑for‑people.org

Silvics Manual www.na.fs.fed.us/pubs/silvics_manual/table_of_contents.shtm

Tree Index www.fs.fed.us/database/feis/plants/tree

Urban Parks www.pps.org

Wisconsin State Herbarium www.botany.wisc.edu/herbarium

Calendar

For handy up-to-date links to Web sites of interest, be sure to visit www.mnstac.org

About MnsTACThe Minnesota Shade Tree Advisory

Committee (MnSTAC) was established in 1974 by a group of concerned citizens to address the health and well being of community forests. MnSTAC is recognized throughout Minnesota and the country for its expertise, advice, coordination and support for community trees. It is an organization of diverse individuals who represent a broad spectrum of tree-related interests. It fosters and supports local community tree programs across the state so healthy community forests are fully integrated into community development, infrastructure, education and management.

MnSTAC BoArd of direCTorS

President: Ken Simons—763/717-9366Vice President: Michael Max, EnvironMentor Systems, Inc.—763/753-5505Emily Barbeau, City of Minnetonka—952/988-8421Ken Holman, MN Dept. of Natural Resources/Forestry— 651/259-5269Steve Nicholson, Kunde Company—651/484-0114Gary R. Johnson, U of M/Forest Resources—612/625-3765Robert Slater, MN Dept. of Transportation—507/529-6145Kameron Kytonen, City of Andover—763/767-5137

Regional MnsTAC CommitteesSoutheast STACChair: Henry Sorensen—651/388-3625 or 651/385-3674Sec./Treas.: Katie Himanga, Heartwood Forestry, Lake City —651/380-9680

Northeast STACChair: Kelly Morris, City Forester, City of Grand Rapids —218/326-7481Secretary/Treasurer/Technical Advisor: Dan Jordan,IRRRA Mineland Reclamation—218/254-7967

EventsOctober 23-27, 2007, SAF National

Convention, Portland, Oregon. For more information: www.safnet.org

October 25, 2007, Wisconsin Arborist Association Fall Seminar, Wilderness Resort, Wisconsin Dells, Wisconsin. Contact Cory Gritzmacher at cagritz@netwurx.net

October 29, 2007, ISA Leadership Workshop, Champaign, Illinois. Contact: Jerri Moorman at jmoorman@isa-arbor.com or 217-531-2835.

November 10, 2007, Herbaceous Perennials Symposium, Iowa State University, Ames, Iowa. For more information: www.ucs.iastate.edu/mnet/herbaceous/home.html

November 14-15, 2007, Partners in Community Forestry National Conference, Baltimore, Maryland. For more information: www.arborday.org

January 9-11, 2008, Minnesota Green Expo, Minneapolis, Minnesota www.minnesotagreen expo.com

New PublicationsBringing Nature Home: How Native

Plants Sustain Wildlife in Our Gardens. Douglas W. Tallamy. 2007. Timber Press

Building Within Nature. Andy Wasowski. 2006. University of Minnesota Press

Cities as Sustainable Ecosystems. Peter Newman and Isabella Jennings. 2007. Island Press

Design Charrettes for Sustainable Communities. Patrick M. Condon. 2007. Island Press

Summer 2007 • ADVOCATE

Presorted Standard

U.S. Postage

PAID

Permit No. 171

St. Paul, MN

Minnesota Shade Tree Advocate

A quarterly newsletter published by the Minnesota Shade Tree Advisory Committee.

Managing Editorial Group: MnSTAC Education Committee (Emily Barbeau, James Burks, Ken Holman, Gary R. Johnson, Lara Newberger, Jeff Rick, Mark Stennes, and Patrick Weicherding)

Editor-in-Chief: Judy Slater

Design: Creative Services Unit, MNDNR

Material in this newsletter is not copyrighted. Reproduction for educational purposes is encouraged. Subscriptions are free. Articles, news items, photos and videos are welcome.

This publication was produced with the support of the USDA Forest Service, Northeastern Area; State and Private Forestry.

Address inquiries to:

Minnesota DNRDivision of Forestry500 Lafayette RoadSt. Paul, MN 55155

Printed on recycled paperusing soy-based inks.

Minnesota Shade Tree Advocate500 Lafayette RoadSt. Paul, MN 55155-4044RETURN SERVICE REQUESTED

What’s Happening With the Minnesota Tree Inspector Certification Program?Effective July 1, 2007, the administration of the Minnesota Tree Inspector Certification Program (MnTIC) was transferred from the Minnesota Department of Agriculture (MDA) to the Minnesota Department of Natural Resources (DNR).

“The impact on past, current, and future tree inspectors will be minimal,” according to Ken Holman, DNR community forestry coordinator. “Tree inspectors will have a new partner, a new contact, and a new phone number. Everything else will remain the same.”

All records related to the program have moved to the DNR, and the DNR is now the first line of contact for the program. Responsibility for detecting, monitoring, and eradicating new invasive exotic pests will stay with the MDA. Initial certifi-cation training, test administration, and recertification workshops, which are held around the state, will continue to be offered through the University of Minnesota.

For more information about the Minnesota Tree Inspector Program, call 651-259-5300

Mailing Address:Minnesota Certified Tree Inspector ProgramMinnesota DNR500 Lafayette RoadBox 44Saint Paul, Minnesota 55155-4044