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Emerald Ash Borer's Disease

Emerald Ash Borer, or EAB, is a small, metallic-green, invasive wood-boring beetle native to east Asia that attacks and kills ash trees. Adult beetles live on the outside of trees and feed on the leaves during the summer months, while the larvae feed on the living plant tissue underneath the bark. The tunneling and feeding activity of the larvae is what ultimately kills trees. EAB attacks trees of any size, age, or stage of health, and trees can die within two years of infestation.

 It was discovered in Iowa in 2010 on in island in the Mississippi River near the town of New Albin. Since then, the beetle has moved westward through the state, and new infestations have been found on an ongoing basis. People are responsible for its spread, which is caused by the inadvertent movement of infested firewood, ash nursery stock, and other ash items. Early inventory data indicates that there are roughly 52 million woodland ash trees and 3.1 million community ash trees in Iowa. As ash is one of the most commonly planted street trees in the state, EAB will have a huge impact on the forest resources of cities and towns throughout.

Stage One:

Early fall color and leaf drop.  Many ash trees in a group may show the same symptom.
Recommendation: For valuable trees in your yard, treatments at this time can save the tree.  If it is a young, unhealthy, or poorly placed tree, replanting is a better option.

Stage Two:

Tips of branches begin to die.  Leaf canopy is not as full and becomes progressively more sparse as the infestation continues. Typically the top of the canopy dies first and then works down the tree.  You may notice increased woodpecker activity on the tree, small vertical splits in the bark and/or small D-shaped exit holes from the adult bug.
Recommendation: In early stage two infestations, treatment for valuable landscape trees may be an option.  Consult with Dittmer Tree Service.  For later stage two infestations, removal and replanting is advised.

Stage Three:

Most of the branches will be dead or dying. In a last attempt to survive, the tree may send out new shoots on the trunk or at the base of the trunk (called epicormic sprouting). Bark will start to flake off, exposing S-shaped larvae feeding galleries in the wood directly under the bark.  D-shaped exit holes can be seen more easily and adult borers may be seen.
Recommendation: Remove the tree and replace with a different species.

Stage Four:

Tree is dead and could potentially create a hazardous situation.
Recommendation: Remove the tree and replant.

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