Insect Treatment and Prevention

Emerald Ash Borer

Ash Bark Damage

Emerald Ash Borer

The Emerald Ash Borer (EAB) is now in Minnesota and a major threat to Minnesota Ash Trees. Below you will find information on how to identify if you have an EAB problem.

The adult Emerald Ash Borer is often difficult to detect, even in areas of high infestation, because of its small size and short period of activity.

Signs your ash tree will show if its infested will include:

Crown Decline
The typical pattern of crown decline caused by EAB is the top 1/3 dying first and then progressing down the tree.

Epicormic Sprouts
As the top of the tree declines, new shoots may be produced lower on the tree.

Symptoms on Multiple Trees
Detectable levels of EAB infestation will almost always include a number of declining ash in your area. Always look for other ash nearby with similar symptoms.

D-Shaped Exit Holes
Although they are difficult to find, D-shaped exit holes are diagnostic of EAB activity.

Woodpecker Holes
Woodpeckers love EAB larvae and woodpecker holes may indicate the presence of EAB. However, not all EAB infested trees are attacked by woodpeckers and other insect larvae may also attract woodpeckers.

Insecticide Options for Protecting Ash Trees from Emerald Ash Borer

There are several factors to consider when deciding whether to treat your ash trees in order to protect them from the destructive emerald ash borer (EAB). In general:

1. Insecticide can effectively protect ash trees from EAB.
2. Trees that are already infested and showing signs of canopy decline when treatments are initiated may continue to decline in the first year after treatment, and then begin to show improvement in the second year. Trees exhibiting more than 50-percent canopy decline are unlikely to recover even if treated.
3. For detailed information on insecticide recommendations, visit University of Minnesota Extension's emerald ash borer webpage: extension.umn.edu/issues/eab.