When you think of a pest, who comes to mind?
My dog, Oliver, brings his favorite toy to me as soon as I sit down to dinner, thinking that since I am not busy, I can throw it for him. Over and over again! He can be annoying sometimes, but the pest I am writing about today is more than annoying. It has the potential to cause an incredible amount of damage to our forests and landscape trees.
The emerald ash borer is arguably the most destructive forest pest ever seen in North America. The small, bright, metallic emerald-green beetle’s natural range is northern China, Japan, Korea and eastern Russia. It was first discovered in Michigan in 2002, although it’s likely that it was present there and in other areas for a number of years before discovery. It is thought to have arrived in North America via crates or packing materials on cargo ships. It has now been found in Michigan, Connecticut, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Massachusetts, Minnesota, Missouri, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, Wisconsin, and the provinces of Ontario and Quebec.
The female adult emerald ash borer lays eggs in crevices in the bark of ash trees. When the eggs hatch, the larvae, which are cream colored and have distinct bell-shaped segments, chew through the bark and into the cambium of the tree. The cambium is where nutrients and water flow to nourish the tree. As the larvae feed on these nutrients, they form S-shaped tunnels, or galleries, under the bark. The tree becomes unable to transport the nutrients and water it needs and begins to die from the top down. This is called canopy thinning.
In late spring, when the adults emerge, they leave small D-shaped exit holes. Other signs of emerald ash borer infestation are increased woodpecker activity and shoots sprouting from the lower trunk of the tree, called epicormic branching.
Because the majority the beetle’s life cycle takes place inside the tree, the signs of infestation are difficult to see. The news gets worse. Tens of millions of ash trees in the United States have already been killed. There is no chance of eradicating the pest. There are an estimated 900 million ash trees in New York state, and many are in forests that are inaccessible. The current treatment for infestation is removal and chipping of affected ash trees and sometimes other “at risk” ash trees in the vicinity. Emerald ash borers are always fatal to the tree.
It is not a question of if we will experience the emerald ash borer, but when. However, its progression can be slowed, and each of us must do our part to make that happen. Most long-distance movement of the pest has been traced to the transport of ash firewood and ash nursery stock. Many New York counties are under quarantine. Don’t move firewood more than 50 miles from a quarantined area into one that is not under quarantine. Learn to identify an ash tree. If an ash tree seems unhealthy, take a closer look. If you find an insect or larvae that seems suspicious, bring it in to the extension office or contact the Department of Environmental Conservation. If you are planting trees, choose a variety of species.
Most importantly, don’t think this doesn’t affect you. The financial ramifications in infested areas are enormous. Replacement of landscape trees, park trees, even trees falling on power lines, can add up to a huge burden for affected communities, to say nothing of the commercial value of ash and the tourism industry.
I would be happy to provide you with colored brochures and wallet cards to help you identify potential problems, and am available to speak to interested groups and organizations. I have a specimen of the emerald ash borer and larva for you to look at, and samples of the galleries and exit holes. There is never a charge for programming of this nature. Contact me at 561-7450 or email@example.com for more information.
Jolene Wallace is the horticulture program assistant for Cornell Cooperative Extension in Clinton County. Contact her at 561-7450 or firstname.lastname@example.org.