Emerald ash borer still thriving in Michigan

Continue to check your ash trees for signs and symptoms of emerald ash borer. If found, you can choose whether to treat or replace the tree.

Many of us have now heard of the emerald ash borer (EAB) Agrilus planipennis Fairmaire, a destructive invasive insect first identified in Michigan in 2002. Native ash trees have little or no resistance to EAB and natural enemies have had little effect. Many dying ash trees have been reported this spring at residences, in parking lots and along rights-of-way in southwestern Michigan. If you have an ash tree located near one of these infested trees, be aware that your tree may well be at risk of infestation too.

Do you have any ash trees on your property? If you're unsure, you may learn more by viewing the Ash Tree Identification Michigan State University Extension Bulletin, or contacting your local MSU Extension office. The ash tree has been used by municipalities in right-of-way plantings and by businesses in parking lots; the number of trees in an area increases the risk infestation by this beetle.

The next step should be a close visual inspection of the ash trees on your property to see if you can find any signs or symptoms of an EAB infestation. Trees may go through decline and die for several reasons. To determine if EAB is causing the decline or death of trees, visit www.emeraldashborer.info for up-to-date research-based information.

If your tree is healthy, assess the risk to your tree by looking beyond your property to public right-of-ways, neighboring properties and nearby businesses to see if there are additional ash trees in the area. Since native ash trees are quite susceptible to damage by the EAB, you will need to decide whether you want to protect the tree by using preventative insecticide treatments or whether you will let nature take its course.

Research has shown that tree defoliation of 50 percent or less is definitely treatable. If you decide treatment will extend the life of the tree, educate yourself on the researched treatment options at North Central IPM Center’sInsectide Options for Protecting Ash Trees from Emerald Ash Borer. Also available at this website are suggestions about what to look for in hiring an arborist. If you decide to let nature take its course, there are several articles at the same website with homeowner information on hiring a tree company, information on removal of infested ash wood and re-planting options.

Emerald ash borer was probably transferred from its native Asia to the United States on solid wood-packing material carried in cargo ships or airplanes. The adult beetles nibble on ash foliage but cause little damage. The larvae (the immature stage) feed on the inner bark of ash trees, disrupting the tree's ability to transport water and nutrients. It has been determined that EAB first caused death of some ash trees in the Detroit area in 2002, but this nasty little beetle went undetected for four years. The nation’s educators with doctorate degrees in entomology, forestry and pathology have been researching this beetle and have gained an understanding of its lifecycle, habitat, treatment options, tree replacement choices and lastly, responsible handling of the timber.

Additional resources at: www.emeraldashborer.info

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