2003 Issues

VOL. 5, NO. 4

Fall 2003

COMMUNITY FOREST PROFILE

CITY green: A Computer-based Tool for Urban Ecosystem Analysis ities throughout Minnesota are struggling with similar issues – a decline in ability to protect their natural resources in a time of population increases and development pressures, a decrease in urban forest and open space resources, an increase in capital improvement and maintenance costs, and the inability to provide much needed infrastructure services in light of escalating costs. Times are so tough in fact that many cities are not able to meet federal and state mandates for attaining clean air and water.

In light of these trends, the environmental challenges faced by our cities are more complex now than at any other time in history. New concepts and approaches are needed to find constructive solutions to environmental issues. This article focuses on urban ecosystem analysis to highlight its merits and shortcomings and to describe the computer-based tools and methods in which urban ecosystem analysis can be applied to provide information to decision makers at the community level.

CITYgreen continued on p. 2

MNDNR

C

By Patrick Weicherding

Downtown St. Paul’s Mississippi Riverfront, as viewed from the old High Bridge. 

Inside THIS ISSUE 2 President’s Corner

6 Clip & Save: Good News for the American Elm 9 ISA Conference Montreal 2003 10 Sudden Oak Death 13 Red Wing’s Flower Baskets 15 STAC Info and Calendar

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

Visit MnSTAC on the Web at www.mnstac.org

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PRESIDENT’S CORNER

It Takes A Disaster...

Sometimes a natural disaster leads to an opportunity.

Our urban forests have faced three natural disasters this summer: a surge in Dutch elm disease (DED), trees ravaged by storms, and drought.

What are our options? Well, we can 1) wring our hands and fret amongst ourselves about the canopy loss, or 2) roll up our sleeves, save what we can, and jump at this opportunity to advocate and educate.

I opt for the latter. Folks are ready to listen - right now! The recent shade tree losses present a teaching moment. This is our chance to enlighten policy makers and enlist new allies: folks who have a fondness for the grand, old trees that line their streets and shade their homes.

This past summer, I have fielded call after call from concerned local residents, wondering what they can do to stem the tide of DED. Some didn’t even realize that the tree on their boulevard was an elm, until it was marked for take-down with a ring of orange paint. Recognizing the budgetary constraints on local units of government, people are offering to open their wallets and pay for “chemotherapy” for their beloved elms. One Minneapolis neighborhood took a proactive approach. Led by a Tree Care Advisor, concerned citizens formed a Tree Watchers group. They attended training sessions on how to identify the early symptoms of DED and learned about Alamo®, Arbotect®, root-graft disruption, etc. Many are willing — eager, even — to pool their resources to stave off further outbreaks of DED in their neighborhood.

In addition to readiness to learn about DED, people want to know what to plant where their storm-toppled tree once stood. Tree autopsies conducted by tree experts after recent storms revealed that many boulevard trees failed because their root systems had been compromised by sidewalk and street repair. When the tree experts recommended that private yards rather than narrow boulevards were better places for big trees, some homeowners quipped that they’d have moved on by the time a new boulevard became a future problem. Another teaching moment in the making!

When trees are front-page news, albeit tragic, that’s our cue to make connections with decision-makers and property owners. Having a receptive audience is half the battle won! The rest is up to us. Advocate. Supplicate.

Educate. Before it’s too late.

Lorrie Stromme is president of the Minnesota Shade Tree Advisory Committee (MnSTAC) and works for the City of Minneapolis.

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CITYgreen, from p. 1 What is an “urban ecosystem?”

An urban ecosystem consists of the natural resources and the human-made structures in and around the places where most people live and work. These urban ecosystems face unique challenges in comparison to their more rural counterparts. Their management boundaries are often drawn at artificial municipal limits, rather than along more natural ecosystem boundaries such as watersheds. As communities become more “urbanized,” the natural landscape changes. Physical changes are made to the topography, vegetation, hydrology, and wildlife habitat. Urban ecosystems also function very differently from rural landscapes in the way that they cycle water, air, and nutrients.

Traditionally, urban and suburban infrastructures are designed to function independently from natural ones, and often they are in conflict with one another. Storm water systems like retention ponds and storm sewers, for example, are engineered to bypass the natural storm water flow in an attempt to control or prevent flooding. These infrastructures are designed for fast drainage, not to utilize the energy, moisture, or nutrients from the hydrologic cycle. Engineering for rapid water removal requires a costly infrastructure of curbs, gutters, and sewers.

Increased impervious surfaces, like roads and parking lots along with the rooftops and driveways for buildings, generate increased runoff. While nature has a built-in system to efficiently cycle precipitation, most urban and suburban methods for handling runoff create a host of problems: pollution, failure to recharge groundwater, and loss of land, waterways, and wildlife. Removing this natural system for cycling water produces many external costs for communities in addition to the loss of economic benefits provided by natural resources. Municipal leaders need to face the challenge of the built environment’s impact on natural ecosystems if they have any vision for building sustainable communities.

Studies show that trees in our urban ecosystems provide numerous environmental and social benefits directly related to restoring and maintaining natural systems. They help reduce air pollution, provide wildlife habitat, prevent sediment erosion into streams and rivers, and are aesthetically desirable. Most Fall 2003 • ADVOCATE

Traditionally, urban and suburban infrastructures are designed to function independently from natural ones, and often they are in conflict with one another.

take advantage of the benefits they provide.

Through the use of Geographic Information Systems (GIS) technology, communities can translate their ecological benefits into economic value for residential energy conservation savings, air quality improvement, storm water management, wildlife habitat, and tree growth for carbon storage and sequestration.

Planners and local decision makers can use this GIS technology as a tool for effective decision making.

The full-color reports from various cities that have conducted an Urban Ecological Analysis can be found on American Forests web site at www.americanforests.org. These cities are using the findings from the analysis to support an ecological approach to solving the built environment’s impact on natural communities.

What is CITYgreen? people have a general sense of the many benefits trees provide, for shade and cooling, for protection from cold winter winds, for physical and emotional well-being, and for beauty. In fact, recent research provides tangible evidence that trees play a valuable role in maintaining the ecological health of our communities — as part of the urban ecosystem. However, the value of trees and other natural resources are often overlooked in community development efforts. Municipal managers frequently lack the necessary information (hard data) to make urban forest resources a priority in their budget requests, and planners lack the information necessary to incorporate trees and forests in their designs.

CITYgreen is a Windows-based software package. It is technically a third-party GIS extension of ArcView® 3.x, which was developed by Environmental Systems Research Institute (ESRI). (Extensions consist of databases, scripts, and other objects that expand the capabilities of the base GIS software and/or provide shortcuts that simplify various tasks or calculations. The software uses embedded formulas and parameters to calculate tree benefits from information that is stored in a GIS. ArcView® extensions such as CITYgreen can only be used in conjunction with ArcView® 3.x.). A detailed description of the current version CITYgreen 5.0 can be found at: www.americanforests.org/ productsandpubs/citygreen/.

What is “urban ecosystem analysis?”

CITYgreen 5.0 actually provides two different ArcView® extensions: CITYgreen Local Analysis and CITYgreen Regional Analysis. The Local Analysis extension can be used to calculate the economic value of a particular neighborhood greenspace, providing measurements of trees’ contributions to stormwater runoff reduction, energy conservation through shading, air pollution removal (ozone, sulfur dioxide, nitrogen dioxide, particulates 10 microns or less in size [PM10], and carbon monoxide removal), carbon storage and sequestration, urban wildlife habitat, and tree growth. As the name implies,

In an attempt to help decision makers and planners incorporate the urban forest into the planning process and their efforts to build more sustainable communities, American Forests developed a new process called “Urban Ecosystem Analysis.” The process maps, measures, and calculates the benefits of urban vegetation and greenspace. It uses satellite imagery and low-level aerial photography along with CITYgreen, a software program, to help communities understand their urban forest resources and ADVOCATE • Fall 2003

CITYgreen continued on p. 4

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CITYgreen, from p. 3 the Regional Analysis extension is used for regional analyses that cover a wider area. The Regional Analysis extension includes tools for detecting change in vegetation cover using certain types of satellite data and for calculating tree benefits on the scale of a large watershed.

Urban Ecosystem Analysis using CITYgreen is accomplished through a seven step analysis that uses satellite data and lowlevel aerial photos: 1. Regional Analysis – Identify the Distribution of Vegetation Cover and Existing Land Use. First, using multi-spectral satellite imagery (Landsat Thematic Mapper) create a classification algorithm to distinguish areas with vegetation from those without vegetation. The result is a land cover image of the region. Second, identify the land use in the region in order to create an informative map of the total urban ecosystem.

Existing land maps like zoning maps can be used in this step.

2. Regional Analysis – Determine Ecostructures. To create an Ecostructure map, vegetation cover information about the natural environment and simplified land use information about the “built” environment from the previous step are combined. (“Ecostructure” describes both the ecological composition and built features of the land).

For example, “medium vegetation / low density residential” is a common pattern that would have its own ecostructure designation.

The ecostructure map helps guide the selection of sample sites for local analysis in the next step.

3. Local Analysis – Select Sample Sites and Inventory. Select the sample sites through random stratification in order to adequately represent each ecostructure. The scanned and map rectified aerial photographs are digitized and entered into the GIS. Field work is scheduled and completed to collect data such as tree categories, size, health class, etc.

4. Local Analysis – Perform Local Analysis. Once the data collection and digitization are complete, run the CITYgreen software program, for example, to determine carbon storage and annual carbon sequestration.

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5. Estimate City or Regional Conditions – To determine the value of the urban trees within a city, the findings from sample sites are applied to like ecostructures and extrapolated to the whole city.

6. Regional Analysis – Conduct Analysis of Heat Island Effect. Map surface temperatures using Landsat thermal band satellite imagery and compare with the ecostructure map.

7. Local Analysis – Energy Conservation.

Use the CITYgreen software to calculate energy conservation savings from the ecostructure map.

Is CITYgreen for the Tool for You? Computer-based tools increasingly are being used for community planning. They have several strengths. One strength is speed: Many programs, even those with enormous data inputs, can be executed on a personal computer in a matter of minutes. Another strength is graphics: For example, a computer based model can be used for scenario analysis, with graphically displayed results, and the scenarios can be modified easily and then visually displayed. A third strength is their ability to handle complex, multi-faceted issues: Some software packages have the capability of integrating a number of different factors. A fourth potential strength is their ability to systematically track results: Tools have been developed to support a variety of management uses, from budgeting to measuring progress.

There are, however, potential drawbacks as well. One is cost. Software modeling programs range from a few hundred dollars to upwards of $20,000 (The cost of the current version of CITYgreen, 5.0, is approximately $900 and ArcView® 3.x is approximately $1,200), and the cost does not stop with the software and the equipment to run it on. In addition, technical expertise may be needed to run the program (A good working knowledge of how to use ArcView® is a prerequisite for successfully using CITYgreen 5.0. The software interfaces for CITYgreen 5.0 and ArcView® 3.x are not completely intuitive, so unless you use these applications frequently, you may need to refer frequently to the manuals for help). A second potential drawback is the data sets that may be needed Fall 2003 • ADVOCATE

as input to the program. While data may have been collected through various means, the data may not be suitable for input into the computer-based program (CITYgreen 5.0 and ArcView® 3.x require access to satellite imagery and low-level aerial photography).

A third potential drawback is the difficulty of adapting a software package to a community’s particular needs. If a program goes beyond the basic building blocks of spread sheets and geographic information systems (GIS) and deals with specific factors and relationships, the program (and possibly the computer) will likely require modification, which may take time as well as money to hire the necessary expertise (Users of CITYgreen 5.0 and ArcView® 3.x have reported this problem in the past). And while technical support may be included as part of the purchase price (No online support for CITYgreen software is available at the American Forests web site at the time of this review), there may be additional charges. Finally, some computerbased tools may quickly become outdated, necessitating periodic updates not only of the computer-based tool but of the computer (CITYgreen software has been revised five times since 1996 and running the software on computers running Windows 2000 or Windows XP may be problematic).

ware requires digital ortho photography (that is, pictures used in the CITYgreen program must be ortho-rectified – given the geometric qualities of a map – before the software will work) and at this point in time such data may be limited to selected cities in the state.

In conclusion, there is no question that CITYgreen has been a huge step forward in conducting urban ecosystem analyses but we must keep in mind that modeling environmental benefits provided by trees and other vegetation is an ongoing topic of research.

CITYgreen provides such modeling capabilities to non-experts at a reasonable cost to the community, which is both its strength and weakness. By allowing routine calculations or tree-related environmental benefits, CITYgreen provides a way to take these benefits into account in urban forest planning on both a local and regional scale. Nevertheless, the recipe approach used by CITYgreen has the potential to result in flawed or unrealistic analyses in the hands of the users that do not appreciate the intricacies and uncertainties involved in these analyses.

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

With specific reference to CITYgreen, the Association of American Geographers reported that when using the software to assess nine study sites in a dense urban neighborhood in Los Angeles “CITYgreen does not calculate energy savings for structures larger than single family residences, reducing its utility in urban environments.

They also reported that “Carbon sequestration and air pollution removal modules worked well, but did not incorporate the best available science.” Finally, they reported that the “Wildlife analysis falls short of its potential, given the extensive field data collected to use the program.”

American Forests provided me with a demonstration copy of its CITYgreen 5.0 software package. My initial reaction was that while the purpose of the software is to map urban ecology and measure the economic benefit of trees, soils, and other natural resources, its ability to incorporate more than one dimension of community sustainability is extremely limited. The data requirements seem moderate to significant, in that the softADVOCATE • Fall 2003

5

Good News For The American Elm

F

MARK STENNES

By Mark Stennes

Good News For American Elm

or more than five thousand years, elm trees have been planted throughout Europe and Asia. In addition to their natural beauty, elms possess functional properties that are important to human beings.

Elms have been used for fuel, wood products, fodder for cattle, If it turns out to be substantially tolerant of Dutch elm disease, this windbreaks, local tree will bear the name “St. Croix.” shelterbelts, and  shade. Individual nary ability to survive construction activity and trees have served as landmarks associated with grade changes. The tree will tolerate flooding, historic events, thus giving a living presence to drought, salt and a wide range of soil pH. Its history. From an ecological point of view, the natural geographic range covers Saskatchewan elms’ contribution to biodiversity and the flow to Nova Scotia to Florida to Texas, and all of energy in north temperate terrestrial ecosyspoints in between. For these reasons, the tems is significant.

American elm is widely admired.

The genus Ulmus, meaning elm, includes many species that occupy sites in the Northern DUTCH ELM DISEASE Hemisphere. The American elm, (Ulmus Americana), is highly valued for its natural As might be expected, the American elm, beauty and desirable characteristics. Perhaps a tree with so many desirable attributes, has the American elm’s most endearing feature is been overplanted. With American elm lined its unique vase-shaped growth pattern. Standing up shoulder to shoulder along boulevards and alone in the open, or in arching cathedral rows, parkways, and prominently featured in resithe American elm displays legendary beauty. dential sites, the risk of importing a destructive pest or pathogen is high. While it is now clear Complimenting its attractiveness is the fact how inevitable it was, we were not prepared to that the American elm can thrive on a wide deal with an imported vascular pathogen like variety of sites and soils. What other tree will Ophiostoma ulmi, the fungus that causes Dutch grow on narrow boulevard strips, or turn up elm disease (DED). sidewalks, curbs and streets, while developing such magnificent proportions? The American Since it was first identified in North elm also tolerates low oxygen levels in soil that America in 1930, DED has killed millions of result from disturbances such as compaction elm trees. Billions of dollars have been spent to and impervious surfaces. It has an extraordiremove dead and diseased trees. This cost does

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Fall 2003 • ADVOCATE

not include the loss of value of the affected urban forests and the heartache suffered by those who have lost their elm trees. We now know that aggressive management by sanitation (finding and promptly removing diseased trees) is cost effective and will substantially reduce loss rates for municipalities with a large population of susceptible elm trees.

Minneapolis, for example, still has at least 90,000 mature American elm trees on public and private property. We also have preventive and therapeutic treatments whose effectiveness is well established.

Among the more unfortunate long-term results of DED, however, is the fact that American elm has been almost completely removed from our list of choices when we have a space for a new tree. As a species, the tree is too susceptible; the risk of DED is just too great.

BREEDING FOR RESISTANCE Breeding research with Asian and European elms, across Europe and America, has resulted in many named cultivars of elm that substantially resist DED. There is a long list of cultivars with varying levels of resistance to DED, elm leaf beetle and elm yellows, but none of them compare to American elm. Much of the problem with breeding DED resistance into American elm is the fact that the American elm is the only member of the elm genus that is tetraploid, meaning that it has four sets of genes instead of two.

It will not cross with the diploid (two sets of genes) species of elm that have shown DED resistance.

The good news is that all elms have defenses, and even in American elm, they work more often than not. But when defenses are insufficient, the tree dies. Mechanisms of defense can be divided into two broad categories: physical features and reactive mechanisms. Physical features can help the plant resist invasion by a pathogen. Physical features that fight DED are springwood vessel diameter, length and grouping. In general, the American elm has large, long, tightly grouped springwood vessels. This is one factor that contributes to its general susceptibility.

The second defense category, reactive mechanisms, includes vessel occlusion in

ADVOCATE • Fall 2003

response to infection, and the ability to wall off the infection and enclose it in new wood. There are also fungitoxic chemicals (phytoalexins) that the plant can produce in response to infection and use defensively against a pathogen. In general, dependable combinations of defensive mechanisms rarely exist in American elm.

In fact, our collective experiences with DED have led us to believe that they may never occur. However, plant geneticists and plant pathologists, particularly at the U.S. National Arboretum, has shown that, once in a while, a significant level of tolerance does exist in American elm.

By screening certain diploid non-American elm cultivars, that have proven resistance to DED, with individual American elm trees that seem to have an unusual ability to survive high disease pressure in the wild, and challenging them with an unnaturally severe form of inoculation, Dr. Alden M. (Denny) Townsend found that a few individuals have substantial tolerance for DED. Semantically, tolerance implies that the plant can become infected, show symptomatic wilting, and then recover without long-term damage. Analysis of his data showed that, over time, cultivar or selection was a highly significant source of variation for crown dieback and survival. While natural tolerance may occur in less than one in 100,000 individuals, once tolerance is identified in any given individual, it can be given a name and cloned an unlimited number of times.

DISEASE TOLERANT CULTIVARS OF AMERICAN ELM ‘Valley Forge’ & ‘New Harmony’ Neither of these clones had names when Dr. Townsend first inoculated a large group of them in 1992. The names were applied by the time he reported the long-term results of the study in June 2001. Ninety-six percent of the ‘Valley Forge’ survived after seven years, and 86% of the ‘New Harmony’ survived.

I have a ’Valley Forge’ that started as a rooted cutting in 2000, and the growth rate is phenomenal. Training pruning is very important in the early years to maintain structural discipline, but it is a true American elm, and Good News continued on p. 8 Good News continued on p. 8

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Good News, from p. 7 appears to be hardy in Minnesota. I have no personal experience with ‘New Harmony,’ and while it is clearly quite tolerant of Dutch elm disease, it has been characterized as somewhat “shrubbier” than ‘Valley Forge’ or ‘Princeton.’

Since neither clone is copyright protected, there are no restrictions on production from rooted cuttings.

Selected references: Campanella, Thomas J. 2003.

Republic of shade: New England and the American elm. Yale University Press. New Haven and London.

‘Princeton’ The American elm cultivar ‘Princeton’ was released in the early 1920’s by Princeton Nurseries of New Jersey, about ten years before the arrival of the Dutch elm disease pathogen. It was selected because of its superlative display of the horticultural features that we like best in American elm, and because it showed the greatest tolerance for many of the other important elm maladies of the day. It was included in Dr. Townsend’s study, and performed as well as ‘Valley Forge.’

‘Princeton’ is not copyright protected. To learn about ‘Princeton’, visit the website: www.riveredgefarms.com.

Dunn, Christopher P. (ed.). 2000.

The Elms: Breeding, Conservation, and Disease Management.

Kluwer Academic Publishers. Boston. USA. Sticklen, Mariam B., and Sherald, James L. (eds). 1993. Dutch elm disease research: Cellular and Molecular Approaches. SpringerVerlag. New York. USA.

at the Department of Plant Pathology at the University of Minnesota. They may be ready to ship by spring 2004.

In summary, there are now at least three available cultivars of American elm that substantially tolerate DED. In general, local wholesale nurseries do not grow them, and local nursery outlets do not provide them. If you want one of these cultivars, you must ask for it, and if refused, then just leave. Seeing a sale walk out the door is very good incentive for suppliers to meet our requests. If you are responsible for letting landscape contracts, specify and insist on the DED tolerant cultivars. There are thousands of good sites available for disease tolerant American elm.

Mark Stennes is a plant pathologist and consulting arborist.

‘American Liberty’ multiclone This cultivar is a combination of six cultivars first released by the late Dr. E. B. Smalley of the University of Wisconsin. One of the six was used in Dr. Townsend’s study, but performed very poorly. The multiclone is copyright protected, and is only available through the Elm Research Institute in New Hampshire.

Townsend, A.M., Bentz, S.E. and Johnson, G.R. 1995.

Variation in Response of Selected American Elm Clones to Ophiostoma ulmi. J. Environ. Hort.

13(3):126-128

St. Croix There is a large and beautiful, type-specimen American elm growing in the St. Croix river valley near Afton, Minnesota. The tree is 72 inches in diameter, about 75 feet tall, and has a crown spread of over 100 feet. It is not just surviving, but thriving in spite of 30 years of exposure to a crown fire of DED. American elm is not just an indigenous component of the natural plant community there, it is an aggressive one. Trees all around it, most of them grown up since their parents were killed, are still dying and breeding bark beetles that feed in the crown of this tree. The statistical probability of a lucky “escape” in this case is prohibitive. There is a possibility that this individual is substantially tolerant to DED and Dr. Townsend has agreed to include it in new trials. Rooted cuttings are being created

Townsend., A.M. & Douglass, L.W. 2001. Variation among American Elm Clones in Long-term Dieback, Growth, and Survival following Ophiostoma Inoculation. J. Environ.

Hort. 19(2):100-103.

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ISA CONFERENCE MONTREAL 2003

by Kelly Fleissner Getting There

M

y international travel experience consists of driving across the Canadian border for fishing trips. Entering Canada has usually been a very simple, stress-free experience. To make sure my trip to the ISA Conference in Montreal worked without a hitch, I carefully did my homework by reading the airline web site and talking to friends who have recently traveled by airline. I’ve always felt that the key to a trouble free trip is to be prepared.

Betty, my lovely wife, and I have not taken a trip together, without the kids, for about thirteen years. We were both pretty excited about the opportunity to travel to Montreal.

Everything we heard about Montreal sounded great. ‘Beautiful city, cosmopolitan, European, great food, diverse culture, something for everyone’ were some of the descriptions given to us.

And I was really looking forward to my first ISA Conference.

With our babysitters, reservations, and plans in place, we arrived at the Duluth International Airport an hour and a half before our flight was scheduled to leave. After a short wait in line, a serious flaw in my preparations was revealed when the ticket agent told us that we weren’t going anywhere without a passport or a birth certificate. Instant panic! Nothing that I had read or been told said we needed those papers. It was not going to be easy to quickly get home and look for the papers and still catch the flight. We called home and directed Anna, our oldest daughter, to start searching for what we needed.

would travel alone. Back to the airport, where we meet the same ticket agent. Another shock.

Since we had booked our plane reservations together, we had to fly together, or neither one of us could go! I wonder what my blood pressure was at that moment? The ticket agent said there was a later flight leaving Duluth that would still get us to the Minneapolis/St. Paul International Airport in time to catch our flight to Montreal. So we went back home again.

One last try to find the paperwork to save the trip.

By now, our house looked like a tornado had hit it. The only thing we could find for Betty was a passport issued in 1984, expired in 1994, with her maiden name on it. A call to the airlines gave us a ray of hope. If we could find our marriage certificate, we could go! We found our marriage certificate and once more, we headed for the airport.

At the airport, the ticket agent carefully examined our papers, then issued our boarding passes, with just enough time to make the flight. We thanked her profusely. As we turned to rush for the gate, the ticket agent stopped us to recheck our boarding passes. All we could think is what now!? We waited 30 seconds (it seemed like 30 minutes) while the agent typed on her computer. Then she gave us new boarding passes. Our seats had been upgraded to first class! The first class flight to Minneapolis, plus a couple of nice drinks, was a great way to set the mood for a great trip.

ISA continued on back cover

Back home, we ravaged through files and scrapbooks. Our hopes quickly faded. We could only find my birth certificate. Since we could not find Betty’s papers, we decided that I ADVOCATE • Fall 2003

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R

emember oak wilt and oak decline? Well, identifying oak diseases and dealing with the problems that go with them just got a little harder. Say “Hello” to Sudden Oak Death (SOD), caused by the fungus Phytophthora ramorum. Until recently, this disease had only been identified in California and southwestern Oregon and scientists hoped that it would not spread. However, this past summer brought confirmed reports of the disease in containerized rhododendrons in nurseries in Washington and British Columbia.

First reported in California in 1995 on tanoaks (Lithocarpus densiflorus), SOD has been identified as the cause of death for tens of thousands of tanoaks, coast live oaks (Quercus agrifolia), and California black oaks (Q. kelloggii). Other plants can also be infected, and although they may not be killed, they can help spread the disease by serving as a source of the disease. This pathogen has been confirmed on numerous non-oak hosts including Rhododendron spp., huckleberry (Vaccinium ovatum), bay laurel (Umbellularia californica), madrone (Arbutus menziesii), bigleaf maple (Acer marcophyllum), manzanita (Arctostaphylos manzanita), California buckeye (Aesculus californica), and even poison oak (Toxicodendron diversilobum). Table I lists additional hosts.

Symptoms Oak wilt and oak decline, two common causes of oak death, may not be easy to distinguish from SOD if it is ever found in Minnesota. The disease is called “Sudden Oak Death” because the whole crown of the tree appears to die rapidly with the foliage turning from a healthy green to brown in several weeks (very similar to oak wilt). However, the actual time from initial infection to noticeable symptom development may be several months to several years. P. ramorum only infects the above ground portions of the plant causing two basic types of diseases: A non-lethal foliar and twig infection (such as occurs on Rhododendron), and a lethal branch or stem infection (found on oak).

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Sudden Oak Death

By Cynthia L. Ash

TABLE 1. KNOWN HOSTS FOR PHYTOPHTHORA RAMORUM COMMON NAME

SCIENTIFIC NAME

Coast live oak California black oak Shreve’s oak Canyon live oak Tanoak Madrone Evergreen huckleberry Manzanita Mountain laurel Andromeda Ornamental rhododendron Bay laurel, Oregon myrtle Bigleaf maple Toyon Salmon berry California buckeye Coffeeberry Cascara California hazelnut Honeysuckle Viburnum Poison oak Western starflower Coast redwood

Quercus agrifolia Q. kelloggii Q. parvula var. shrevei Q. chrysolepsis Lithocarpus densiflora Arbutus menziesii Vaccinium ovatum Arctostaphylos spp.

Kalmia latifolia Pieris spp.

Rhododendron spp.

Umbellularia californica Acer macrophyllum Heteromeles arbutifolia Rubus spectabilis Aesculus californica Rhamnus californica Rhamnus purshiana Corylus cornuta Lonicera hispidula Viburnum spp.

Toxicodendron diversilobum Trientalis latifolia Sequoia sempervirens

Fall 2003 • ADVOCATE

On oaks, P. ramorum does not appear to infect small branches or leaves (as it does on tanoak) resulting in infection and mortality more commonly associated with large trees and not seedlings and saplings. Opportunistic organisms (those that take advantage of weakened or dying plants) including ambrosia beetles, bark beetles, and a sapwood rotting fungus

DAVE RIZZO

On oaks and tanoak, large, localized infections, called cankers, occur on the stems.

Black or reddish ooze often seeps from the cankers, staining the outer bark.

Removing the outer bark will expose the dead inner bark tissue surrounded by black lines, called zone lines. Unfortunately, these symptoms can be confused with symptoms caused by other species of Phytophthora that occur in Minnesota so laboratory tests must be done to confirm the presence of P. ramorum.

Discoloration in the infected cambium of a rhododendron due to P. ramorum. 

called Hypoxylon thouarsianum, may be abundant on dying trees.

MATTEO GARBELLOTO

Early detection will be important for successful eradication if SOD is ever found in Minnesota. Every effort should be made to identify the cause of death of red oaks. In particular, dying red oaks planted near rhododendrons should be closely inspected for symptoms of SOD. This is especially true since widely traded rhododendron ornamentals can be infected with P. ramorum and the susceptibility of some important red oak species has been demonstrated.

Coastal live oak with seepage from P. ramorum infection. 

SOD continued on p. 12 ADVOCATE • Fall 2003

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Quick Review

of

Oak

Decline

Declines are slow-acting complexes of several agents that rob the tree of its health and fail to allow it to recover. Agents include prolonged drought, spring defoliation (caused by insects, frost, or anthracnose), Armillaria and other root rot fungi, and boring insects such as the two-lined chestnut borer.

Even flooding, mechanical damage (wind storms, construction, improper pruning), and chemicals can be included in the list of decline agents. Symptoms of decline appear and increase gradually over time and may be variable, depending on the agents involved.

A progressive dieback of the crown is the most obvious symptom.

Dark staining may be present on the trunks of declining trees. Oak decline causes a slow decline over 3-5 or more years whereas SOD causes a rapid decline (1-2 years).

The rate and pattern of tree decline may need to be determined visually by an experienced arborist or forester.

& Oak

Wilt

Oak wilt,caused by the fungus, Ceratocystis fagacearum, is an aggressive pathogen of oaks in the red oak group. Red oaks have pointed leaf lobes, as opposed to white oaks which have rounded lobes. Symptoms include wilting and marginal scorch of the foliage, premature leaf drop, and rapid death of the tree. Oak wilt does NOT cause cankers or bleeding from the trunk. However, the disease is present in the vascular tissue and generally results in staining under the bark of infected trees, however, there are no conspicuous zone lines.

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SOD, from p. 11

MDA Surveys for Sudden Oak Death

I

interim SOD report can be n 2002, the Minnesota found at the MDA website: Department of Agriculture www.mda.state.mn.us/ was one of a few states cominvasives/suddenoakdeath/ pleting surveys for sudden default.htm. oak death (SOD) beyond on-going work in California An expanded SOD surand Oregon. Over twentyvey this spring was recently five nurseries considered completed.

A total of high risk for introduction samples from 25 nurseries of SOD were surveyed by were collected.

As with last examining rhododendrons fall, standard culturing for the and oak trees. A total of 161 disease will occur and followsamples were collected durup PCR analysis of suspect ing the fall. The good news cultures will proceed. Even is the disease was not found though final analysis is ongoat any sites. The fall survey ing, visual observation of was regarded as highly sucfungal cultures so far show no cessful at a national confersigns of SOD. Final results ence and the direct result of will be reported later this cooperation from nurseries, summer with results posted at the MDA (Agronomy and the website listed above.

Plant Protection Division and Laboratory Services Division), Cynthia L. Ash is a plant patholoUniversity of Minnesota Plant gist.

Disease Clinic, USDA-FS State and Private Forestry, and USDA-FS North Central Forest Experiment Station.

The MDA could not be happier for the roles each played and how well For additional information on each conducted Sudden Oak Death visit: their part.

• www.apsnet.org/online/SOD (also has a nice A links page) copy of • www.na.fs.fed.us/spfo/pubs/pest_al/sodeast.htm the

• www.plantmanagementnetwork.org/pub/php/ diagnosticguide/2003/sod/ • www.mda.state.mn.us/invasives/ suddenoakdeath/default.htm

Or call: Anne Selness, Minnesota Department of Agriculture, 651-296-8448

Fall 2003 • ADVOCATE

Red Wing’s

Flower

By Judy Slater

ed Wing, Minnesota, population 16,000, is a beautiful town located on the banks of the Mississippi River. Visitors and residents enjoy the city’s historic buildings, antique shops, performing arts, and riverside parks.

Red Wing is one of those “pretty as a post card” type of towns. Perhaps it was the city’s natural beauty that inspired the community to plant some flowers.

“In 1989, sixteen metal flower boxes were placed downtown, in front of the River Front Center and the St. James Hotel,” reports Deanna Sheely with the City of Red Wing.

“The next year, flower boxes were placed in the park between those two buildings. Then someone suggested that hanging flower baskets would have more impact than the flowers boxes. Basically, that’s how it started.”

The Flower Baskets “The initial start-up costs for the flower baskets were paid by the Kiwanis Club,” notes Rick Seyffer, with the City of Red Wing.

“Local business owners donated time and labor, estimated at $10,000, to build the baskets. City workers installed the brackets and assembled the chain hangers. Each basket has a diameter of two feet. The first year, there

ADVOCATE • Fall 2003

THE CITY OF RED WING

R

Hanging flower baskets line the parkway in downtown Red Wing. 

were only twenty flower baskets. The past few years, we have been hanging 300 baskets.”

Planting and Maintenance In March, the empty flower baskets are planted. The city provides materials for 150 baskets to the two nurseries in town - Sargent’s and Halstrom’s. After the nurseries do the planting, the flower baskets hang in the greenhouses for ten weeks. When the danger of frost is gone, usually the third week in May, the baskets are hung outside on city light poles.

Red Wing continued on p. 14

13

Red Wing, from p. 13

“The flower baskets are a symbol of community pride and partnership. And they are a beautiful way to say: Welcome to Red Wing!”

“We water the hanging flower baskets seven days a week all season,” Seyffer reports.

“On average, about 1000 gallons of water are used per day. More water is used when the weather is hot or windy, and less water is needed when it is cool or raining. No watering is done on days when there has been at least one inch of rain with no wind. We do not prune the flowers, however, we do fertilize them.

One basket of flowers weighs 30 pounds in the spring and at the end of the growing season, it weighs 80 pounds.”

Minor Problems Some unexpected problems have occurred with the flower basket program. In the first few years of the program, people would jump up and hang from the baskets. Some of the flower baskets were damaged. Fortunately, this no longer happens.

Another problem happened when access to the flower baskets was blocked during road construction. The city also discovered that trucks with tall exhaust pipes can burn the flowers baskets. And water dripping from the flowers can leave water spots on parked cars.

On the other hand, the city is pleased to report that only one basket has ever been stolen.

Over the Winter Sometime in October, the first frost hits the flowers. After this happens, the flower baskets are left in place for a few days to dry out. Then the baskets are removed. The flowers and soil are sent to the compost pile. The baskets are disassembled and all the hardware is placed in storage.

Over the winter, the flowers basket program is reviewed. Decisions are made for the next planting season. Successful growers, such as wave petunias and ivy geraniums, are included in the baskets every year. New plants are added to the mix each year. Some will grow well and others will have problems.

Lobelia, for example, a small blue flower, did not tolerate the hot weather. It was grown in the flower baskets only one year.

In February, the empty flower baskets are steam cleaned. Necessary repairs, such as spot welding, are done. When the work is finished, the baskets are ready to go back to the greenhouses.

Community Pride The citizens of Red Wing are proud of the flower basket program. They support the program with financial donations to the Kiwanis Club. The Kiwanis Club pays the cost of the flowers and the maintenance.

The City of Red Wing has competed nationally for civic awards and has received international recognition for the flower basket program.

“The flower baskets are a symbol of community pride and partnership,” says Deanna Sheely. “And they are a beautiful way to say: Welcome to Red Wing!”

Further information about Red Wing’s flower basket program is available from the City of Red Wing at www.red-wing.org Judy Slater is the editor of the Minnesota Shade Tree Advocate Newsletter.

14

Fall 2003 • ADVOCATE

STAC INFO & NEWS

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

Calendar

URBAN AND COMMUNITY FORESTRY CALENDAR

Events

New Publications

October 25-29 Society of American Foresters National Convention. Buffalo, New York. www.safnet.org

Harvesting Urban Timber: A Guide to Making Better Use of Urban Trees. Sam Sherrill. 2003 Linden Publishing.

MNSTAC BOARD OF DIRECTORS President: Lorrie Stromme, City of Minneapolis—612/7885157 Vice President: Michael Max, EnvironMentor Systems, Inc. —763/753-5505 Kimberly Thielen-Cremers, Minnesota Department of Agriculture—651/296-6692 Jim Hermann, Mpls Park & Rec Board/Forestry—612/3704900 Ken Holman, DNR/Forestry—651/296-9110 Fletcher Johnson, Xcel Energy—651/639-4590 Gary R. Johnson, U of M/Forest Resources—612/625-3765 Robert Slater, MN Dept. of Transportation —507/529-6145 Kathy Widin, Plant Health Associates, Inc.—651/436-8811

November 5-8 Associated Landscape Contractors of America - Green Industry Expo. St. Louis, Missouri. www.gieonline.com

Primary Succession and Ecosystem Rehabilitation. David Paul Bayles. 2003 University of California Press.

Regional MnSTAC Committees

February 1-3, 2004 Wisconsin DNR Urban Forestry Conference and Trade Show. Green Bay, Wisconsin.

Contact: Brian Cassidy.

Phone: 262.886.5224. Email: casitree@hotmail.com

Southeast STAC Chair: Henry Sorensen—651/388-3625 or 651/ 385-3674 Sec./Treas.: Katie Himanga, Heartwood Forestry, Lake City —651/345-4976

Headwaters-Agassiz STAC (HASTAC) Chair: John Johnson, City Forester, City of Thief River Falls—218/681-1835 Sec./Treas.: Jeff Edmonds, DNR Forestry, Bemidji —218/755-2891

West Central STAC Chair: Bob Fogel, Director of Parks, City of Moorhead —218/299-5340 Sec./Treas.: Dave Johnson, DNR Forestry, Detroit Lakes —218/847-1596

Northeast STAC Chair: Kelly Morris, City Forester, City of Grand Rapids —218/326-7600 Secretary/Treasurer/Technical Advisor: Dan Jordan, IRRRA Mineland Reclamation—218/254-7967

ADVOCATE • Fall 2003

December 3-6, 2003 American Society of Consulting Arborists 2003 Annual Conference. Lake Tahoe, NV www.asca-consultants.org/ conferences.html

February 9-10, 2004 Minnesota SAF Winter Meeting.

Brainerd, Minnesota www.mnsaf.org February 11, 2004 How to Teach Forestry to Kids. Brainerd, Minnesota. Contact Laura Duffey. Phone: 651.296.3406.

Email: laura.duffey@dnr.state. mn.us

Urban Forest: Images of Trees in the Human Landscape. Lawrence R. Walker and Roger del Moral.

2003 Cambridge University Press.

Websites Roof Top Gardens. www.greenroofs.com The Forestry Forum. www.forestryforum.com Why Leaves Change Color. www.esf.edu/pubprog/ brochure/leaves/leaves.htm

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

March 29-31, 2004 11th Annual Trees & Utilities National Conference. Omaha, Nebraska. www.arborday.org/conferences April 22, 2004 Building With Trees Seminar. Minneapolis, Minnesota. www.arborday.org/ conferences

15

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

Managing Editorial Group: MnSTAC Education Committee (Gary R. Johnson, Mark Stennes, Jeff Rick, Ken Holman, Gail Nozal, Patrick Weicherding and James Burks) Editor-in-Chief: Judy Slater judyslater@earthlink.net Design: Creative Services Unit, MNDNR Material in this newsletter is not copyrighted. Reproduction for educational purposes is encouraged. Subscriptions are free. Articles, news items, photos and videos are welcome.

This publication was produced with the support of the U.S.D.A. Forest Service, Northeastern Area; State and Private Forestry.

ISA, from p.9 What I Learned

A. ISA News

D. Tree News

• Membership — 16,341 from 45 countries, 87% male, 65% college degrees.

• More and better disease resistant elms are becoming available.

• Tour des Trees raised approximately $250,000 for research.

• PDA’s are now capable of doing tree inventory and tree risk assessment.

• Tree Climbing Champions — Bernd Strasser and Kiah Martin.

• Emerald ash borer is a devastating problem in Michigan with few control options.

B. Quebec Ice Storm

• A written risk management policy that is followed is critical for cities to reduce their liability for tree failures even if the lack of resources make the reduction of risks prolonged.

• Freezing rain for 80 hours.

• One million homes lost power, some for almost a month.

• One half-inch of ice will cause limb failure. One inch of ice will cause complete tree failure. Ice buildup of four inches occurred in this storm.

Address inquiries to: Judy Slater Minnesota Shade Tree Advocate 115 Green Hall 1530 Cleveland Ave. N. St. Paul, MN 55108 Printed on recycled paper using soy-based inks.

C. Arborist Safety • Commercial fishing is the profession with the highest fatality rate.

• Tree workers, logging, mining, and trucking have the next highest fatality rates.

• The fatality rates for tree workers is about three times higher than police or firefighters.

• Being hit by something is the most common reason for fatalities in tree workers. Falling was previously the number one cause for fatality.

• Chippers kill more tree workers than chain saws.

• Windshield surveys, although less than perfect, can be an effective way of locating high risk trees.

E. Crisis Management • Progression — event, emergency, crisis.

• Sixty-eight percent of all crisis caused by management.

• Be prepared.

• Don’t lie.

• You can’t win a fight with the media.

• Empathy is more effective when communicating during a crisis than honesty, expertise, or dedication.

Kelly Fleissner is a forester with the City of Duluth.

• Chain saws injure more people than chippers.

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

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

Fall 2003 • ADVOCATE