Conservation Corner: Ash trees and the invasive Emerald Ash Borer

Trees, like humans, react to stress in various ways. Both can get sick — sometimes from similar stressors like air pollution or physiological reasons such as not getting enough nutrients to provide health and growth. Most of the time, these stressors are just part of the ups and downs of our ecology.

For trees, however, when the stressor is an invasive pest, those natural defenses no longer work and the invader begins to dominate. In many cases, these invasive forest pests will permanently disrupt and change the makeup of the forest as we know it.

If you haven’t heard about them by now, the pest I am speaking of is the Emerald Ash Borer (EAB). Currently in 35 states and five Canadian provinces, EAB is now in Maine, with detections in York County, Madawaska and surrounding areas in northern Aroostook.

Both areas have a formal quarantine through the Maine Department of Agriculture’s Conservation and Forestry division to help slow the spread of this invasive pest. The quarantine prohibits movement of ash nursery seedlings and will regulate the movement of hardwood chips, firewood and other ash products.

Like many invasive plants that look pretty, the EAB insect is a bit flashy with bright iridescent green coloring. Don’t let its pretty face fool you though. Since its arrival in Michigan in 2002 (likely arriving there by hitchhiking on wood packing material from Asia), EAB has single handedly destroyed hundreds of millions of green, white, and brown ash trees from Wisconsin to Maine.

Adults lay eggs in the bark and after hatching, the larvae feed on the inner bark of the trees, creating long serpentine trails that disrupt the ash tree’s ability to transport water and nutrients.

Ash is an important tree for lumber, firewood and wood products (since this is spring, think baseball bats) and is prevalent in parks and lining our town streets. The seeds of ash are also important food for wildlife and birds. Brown ash in particular is an extremely important tree culturally to the Wabanaki peoples.

What can be done? While the truth is that eventually many ash trees in Maine will succumb to EAB, we can be a part in slowing down that inevitability. Hands down, the most important thing the public can do to slow the spread of EAB is to leave firewood at home.

“Buy It Where You Burn It” is probably the best mantra to repeat as you head off on summer camping trips. The wood may look okay, but insect eggs and/or microscopic fungus spores are often too small to see and can be enough to destroy an entire ecosystem. Who wants to be responsible for that?

We can also become aware of the signs of EAB, as early detection is a key step to combating an outbreak.

Finally, it generally takes 5-10 years for an outbreak to take hold, which provides landowners and municipalities valuable time to plan and decide what trees to save or what areas of your woodlot to cut. There is lots of information about EAB online and the Southern Aroostook Soil and Water Conservation District also has fact sheets available that will help you plan for the one specimen in your yard or a woodlot of ash.

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