EMERALD ASH BORER
Article #93, March, 2005
By Bill Cook
The words "emerald ash borer" increasingly create concern among many people in Michigan, especially forest landowners and homeowners with ash trees. Government agencies and universities have been striving to understand this exotic beetle, determine its distribution, and develop strategies to address a very serious tree pest.
The 2002 discovery
of the emerald ash borer (EAB) happened long after the beetle became well-established
in southeastern Michigan and had been spread to many counties. This "artificial"
spread was largely the result of humans unknowingly moving infested materials,
such as nursery trees, firewood, and logs. In the world of exotic pest eradication,
the EAB presents a formidable task, maybe like slamming the barn door and rounding
up the horses after they ran out.
introduction should have been prevented. However, millions of tons of cargo
reach North American shores every year. Budgets required to inspect significant
portions of imported materials are prohibitive. It is a matter of priorities,
perhaps, but a fiscal reality. In the end, our collective appetite for cheaper
goods will almost certainly bring more exotic pests to our shores.
Emerald ash borers
kill ash trees. There are at least 700 million ash trees in Michigan alone and
all of them are at risk. Ash often serve disproportionately important roles
in many settings, such as in wetlands and riparian zones. In residential areas,
ash has long been a favored tree because of its fast growth, straight trunk,
and until recently, minimal pest problems.
The loss of ash
is one more battle in the exotic species assault on our natural heritage. American
chestnut and American elm have been reduced to a remnant of what they once were.
Michigan butternut and beech are threatened by exotic pests. Balsam fir and
hemlock further east are dying from exotic insects headed this way. The list
continues. Many scientists believe that exotic pests are the single biggest
threat to the diversity and productivity of eastern forests.
to understand that natural spread of EAB is fairly slow in most cases. Studies
by MSU scientists indicate that the beetles move between 0.5 to 2 miles each
year. What appears as rapid spread is actually an improved ability to find EAB.
Finding new and low level infestations is difficult. The borers can be present in an area for several years before the trees begin to decline. Many recently discovered EAB populations have actually existed for at least a few years. Quarantine zones in southeastern Michigan expand as EAB distribution becomes better known.
Trap-tree survey techniques were developed and tried for the first time only last year. Surveys were conducted at fairly coarse grids throughout much of Michigan because of limited budgets. They actually worked better than expected and resulted in the discovery of several "outlier" populations in northern and western Lower Peninsula. The Upper Peninsula, parts of northern Michigan, and northern Ohio and Indiana will be surveyed again this year.
expect additional EAB infestations to be found over the next few years. State
officials have targeted the Straits area for intensive survey and detection
work. If EAB populations are found in the Upper Peninsula, they will likely
be a high priority for eradication.
EAB is not merely
a Michigan or Lake States issue. This exotic pest threatens at least 16 species
of ash that grow across the entire continent. Efforts to reduce the density
of ash in forests to help control the spread of EAB will require a considerable
amount of planning and action, at a level of magnitude not often incorporated
into forest management. Both public and private landowners will need to be involved.
The action might be likened to setting a large backfire to stop the spread of
a wildfire, except the spread of EAB is much slower than a wildfire.
What can a landowner
do? Stay current with EAB information. Visit the website: [www.emeraldashborer.info].
Response to the EAB threat needs to be carefully considered by all property
owners. A single recipe for action simply does not exist. Watch for an MSU Extension
bulletin about EAB for woodland owners this spring.
If your property
is not close to a known EAB infestation now, prepare for the day when new infestations
are discovered on or near your property. Know which species of ash are in your
woodland, where they grow, and how the ash are distributed.
In much of the
Lower Peninsula, outside of the quarantined areas, landowners should consider
harvesting ash trees before quarantines are imposed. The abundance of ash, the
distance from known EAB populations, and the long-term goals of the landowner
are key factors in making decisions. Removing ash will help contain the spread
in mind that ash products such as logs, firewood, or chips cannot be moved outside
quarantined areas without special permission and certificates issued by the
Michigan Department of Agriculture.
In all cases,
work with a professional forester to consider the options. Be wary of unscrupulous
timber buyers. Unless your land is already in a quarantine zone, you have time
to learn about the EAB, work with a forester, and decide what you think is best
for your property. However, don't underestimate the threat of EAB and the role
that you might play in combating this serious pest.
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Bill Cook is an MSU Extension forester providing educational programming for the entire Upper Peninsula. His office is located at the MSU Upper Peninsula Tree Improvement Center near Escanaba. The Center is the headquarters for three MSU Forestry properties in the U.P., with a combined area of about 8,000 acres. He can be reached at email@example.com or 906-786-1575.
by Bill Cook, Forester/Biologist, Michigan State University Extension, 6005
J Road, Escanaba, MI 49829
906-786-1575 (voice), 906-786-9370 (fax), e-mail: firstname.lastname@example.org
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