|
Emerald
Ash Borer and Middleton’s plan
|
The Emerald Ash Borer (EAB) is an exotic invasive
beetle that will have a significant impact on the
city’s urban forest. During the summer of 2009 Wachtel
Tree Science, Inc. conducted an ash tree
inventory and identified 2,335 ash trees along
streets and an additional 261 ash trees on
public lands (parks and Pleasant View Golf
course). This translates to roughly 28% of the
city street trees being ash – well above the
desired urban forestry guideline of 20% for any
genus and 10% for any one tree species.
The following information is intended to provide
information on how Middleton intends to deal with
this issue. For information specific to the insect,
history of its spread, how other communities and
states are dealing with EAB, and other frequently
asked questions, please use the following two links:
Wisconsin Emerald Ash Borer Information Source
National
Emerald Ash Borer Website
Where are the ash trees in Middleton located?
Click on the ward that you live in for a .pdf map
showing publicly owned ash tree locations in your
area. Please note that these maps are rather large to provide greater details so may take some time to load depending on your download speeds. They also do not include
ash trees on private property.
Low Resolution Maps by Ward (Smaller size but less detail)
|
What is the City going to do?
Unfortunately there is no “preferred” response to EAB, we have to look for ways to make lemonade from the lemons we are given. With this in mind, the goal of the city’s EAB program is:
“To minimize the economic and social impact of EAB and the loss of ash trees to the health of Middleton’s urban forest by utilizing the most current information to distribute costs associated with EAB over a manageable time period.”
Public Education
During the summer of 2010, city staff will be conducting numerous public education presentations on the impacts of EAB in Middleton. If you or your group would like to have this presentation given at one of your meetings, please call City Forester/Horticulturist Mark Wegner at
608-821-8345 or by email at
mwegner@ci.middleton.wi.us
View the
EAB presentation now.
Removal of ash trees
In addition to public education the city is also proposing preemptive removal of ash trees on public property over the next eight years prior to the arrival of EAB and replant with a high diversity of tree species. Doing so would allow the city to handle over 50% of the removals and replanting in the city with existing staff – greatly reducing the costs associated with contracting the work out.
This proposal is subject to final approvals from City committees and ultimate approval by the City Council.
Removal of ash trees will be based on health assessments that were conducted during the summer of 2009. Ash trees with the lowest health will be removed first, followed by ash trees with high amounts of deadwood, other structural defects, and ash trees compromised by utility pruning. In addition to these factors, density of ash trees within neighborhoods or along certain streets will be considered.
For example, Spring Hill Drive (between Lynn Street and Companion Lane) has 32 ash trees; a very high density. Under current plans all 32 of these trees would be removed over the next 8 years, resulting in removing of 4 ash trees per year. This will spread out removals over a longer time frame than would likely occur if the city were to wait until EAB arrives. The longer removal period will also lessen the visual impact of removals and spread out removal costs over time. Replacement trees will also result in a more diversified age structure, meaning that the difference in ages (and size) between trees will result in a healthier urban forest.
Why not treat ash trees?
The majority of the ash trees in Middleton are under 14" in diameter at breast height, roughly the size of a frozen pizza you buy at the store. As of now chemical treatments fall into two categories: the method called "root drench" which is mixing the chemical with water and pouring the solution around the base of the tree; and direct injection which is the injection of a chemical into the base of the tree (similar to treatments made now for Dutch elm disease and oak wilt). The root drench method is relatively inexpensive, can be administered by a homeowner but has to be done every year, is best used for small diameter trees (8"-10" maximum in the opinion of the City's Forestry staff). The injection method is more expensive, can only be applied by licensed individuals or companies, but does last for 2-3 years and is better suited for larger ash trees. Independent of the method chosen, both will have to be conducted for the remaining life of the tree and are not 100% effective in preventing EAB from infecting the tree.
For the smaller ash trees being removed, growth rates of replacement trees can reach the size of the removed ash tree in a relatively short time frame. The cost of treating a small ash tree every year could be better used by planting of a new tree that will not have any treatment requirements. In addition, streets with high densities of ash trees would result in the application of large amounts of chemicals within that small area triggering environmental and ethical concerns. Injection of ash trees would require specialized equipment and demand more manpower that the city currently has.
Heritage ash tree treatment plan
There are however six ash trees over 30" in diameter. Given the large size of these trees removal costs will be substantial, making treatment of these trees a viable option. Even with the limitations discussed above, treatment of these trees would be an option the City would like to pursue. If you have any questions regarding the possibility of treating your trees please give us a call (608-821-8345).
Replanting of trees
While removal of the ash tree population is unfortunate, this is an opportunity to diversify Middleton's urban forest.
The city will strive to replant every tree if
possible (ordinance restrictions regarding
intersections and signage will take priority over
tree planting however) keeping in mind the urban
forestry guideline of not having more than 20% for
any one tree species and 10% for any genus. This
means that all maples trees (or oak, locust, linden,
etc.) will not exceed 20% of the total street tree
population. In addition to the diversity provided by this policy, a level of future security will be provided due to the fact that if a new threat to trees is discovered (be it insect or disease) there will no longer be a large number of any one tree species present on our streets.
So what will Middleton replant with? Our most current tree
inventory shows that maple trees are over the
recommended 20% and honeylocust trees are close to
that as well. Does that mean no more planting of these
two genus? Not necessarily. Consideration will be given to the surrounding tree species of the area, and if for example, there are no maple trees nearby, a new maple tree may be appropriate. At the same time the City would like to add diversity and even try some new species that are underrepresented or not present at all in the city now. Think of it as a "salt n' pepper" approach; use of a number of known species that will work as street trees with a few experimental ones scattered where appropriate and fitting to the site.
A full list of
replacement trees is currently being developed, but
the following trees will be considered as ash
replacements (cultivars or varieties not decided
upon at this time).
Links will
send you to the University of Illinois Extension
website except where noted:
|
|
|
