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Emerald Ash Borer
 Emerald
ash borer (EAB) was discovered in St. Paul, near the border of Minneapolis,
in the Spring of 2009.
What is EAB?
EAB is a non-native insect originating from Asia.
Why is EAB harmful to ash trees?
While the adult EAB beetle only nibbles on ash foliage, causing little
damage, the problem lies with the larvae. Female borers lay their eggs
underneath an ash tree’s outer bark. As the larvae grow and mature, they
tunnel and feed on the tree’s inner bark, destroying its xylem and phloem
tissue. This disrupts the tree’s ability to transport water, mineral
nutrients and photosynthetic sugars to all parts of the tree, eventually
killing it.
Multiple species of borers exist in addition to EAB. Borers, in general,
will primarily attack only unhealthy or stressed host plants. In its native
range, EAB works in a similar manner. However, since our native ash trees do
not have any inherent defenses against EAB, all species of ash trees in
Minnesota, whether healthy or not, are susceptible to destructive attacks.
How many trees has EAB killed?
EAB has killed millions of ash trees in an already affected area of 11
mid-eastern states and portions of lower Canada.
How will EAB affect Minnesota, and specifically, Edina?
Minnesota has the third largest population of ash trees in the country. In
urban areas, the ash tree became the predominant “replacement” tree when
trees were lost to Dutch elm disease. The ash tree is also vital to many
natural areas throughout the state.
In Edina, the ash population is estimated at 50,000. The most valuable ash
trees (based on size, health, location and landscape importance) are
primarily situated on residential lots, some parkland and a few boulevard
areas throughout the City. An outbreak could greatly affect the City’s tree
population.
Should I chemically treat my ash trees?
Chemical treatments are available to help protect healthy ash trees or those
minimally affected. If you choose to use chemical protection, keep in mind
that application must take place every one to three years, depending on the
chemical and application method used, and can be somewhat expensive.
The decision to commit to long-term use of chemical protection is a private
one, but some factors to consider are the relative importance and health of
the tree or trees in your landscape and the affordability of a long-term
commitment. As with all trees, ash trees have multiple potential blights or
diseases which will not be helped by EAB protection.
Is chemical treatment effective?
While research has shown rates of effectiveness to vary from chemical to
chemical, no chemical protection method can be 100 percent effective.
What are my other management options?
Another management option -- also widely suggested for Dutch elm disease --
is to consider planting another tree or trees on your landscape to have a
replacement in the event you lose an important ash tree. This option can be
considered whether or not you also choose to chemically treat an ash.
Residents are strongly encouraged to learn more about the disease in order
to respond in a well-informed manner based on the latest factual research.
What is the City doing to prepare for EAB?
The City of Edina is currently considering training in-house personnel to
chemically treat select, valuable ash trees within City parks. We are also
in the process of learning how to inspect and verify the presence of EAB in
trees. Because of the complexities involved in the diagnostic stage, it is
important to have professional or well-trained inspectors. If the City does
choose to use chemical treatments, it is important we are able to correctly
diagnose the disease.
City Park personnel have also attended many meetings and have been studying
all pertinent information regarding EAB to help prepare for the management
of this potentially serious problem.
Is a firewood quarantine in place?
Ramsey and Hennepin counties are currently under Department of Agriculture
quarantines in regard to the movement of ash wood. EAB has a wider spread
when infested wood is moved. If purchasing firewood, be certain it is not
infested with EAB.
For more information on emerald ash borer, call Edina Park Maintenance's
Forestry Division at 952-826-0308.
For additional resources on emerald ash borer, refer to the following
websites:
*Photos courtesy of
Howard Russell and David Cappaert, Michigan State University, Bugwood.org.
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