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Emerald Ash Borer: Symptoms and Treatments

Well, Treasure Valley... we have some potentially upsetting news for you.  The Emerald ash borer (Agrilus planipennis) has been found outside of Portland Oregon this last year, prior to this the furthest west that it was found was in Colorado. This destructive pest has been wreaking havoc in the Eastern part of the country, by decimating the forests of native Ash trees found there. While Idaho does not have native ash forests, there are thousands of highly susceptible ash trees found in our local parks and urban landscapes throughout Boise, Meridian, Nampa, Eagle, and all the surrounding areas.  The Emerald Ash Borer (or EAB) was first discovered in Michigan in 2002. EAB attacks all species of North American Ash. Lifecycle:  Adults emerge May-July. The female will lay eggs in bark crevices hatching in 7-10 days, the larvae bore into the tree where they feed on the inner bark and phloem, creating winding galleries preventing the flow of water and nutrients to the tree and resulting in dieback and death to the tree. Adults can move .5 to 1 mile in a year from infested sites. Signs and symptoms: Crown dieback, Suckers sprouting at the base of the tree, woodpecker activity, D-shaped exit holes. Treatment:  Systemic injections of Emamectin Benzoate, annually can protect your tree investments indefinitely.  While typically cheaper, topical treatments of high rates of Permethrin on the Ash tree Trunk and scaffold branches can also be effective.  However, the timing of this application is critical to the window when adult females are actively ovipositing. ISDA is currently working on a response management plan for the general public and information once released will be updated here. Follow the link for more information: Oregon Department of Agriculture


10497 US-20
Caldwell, ID 83605
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