I had the wonderful opportunity to travel on a professional development opportunity to Colorado last week. I traveled with horticulture and entomology colleagues from across the state to Colorado Springs, Boulder, Denver, and Fort Collins to study how they deal with an almost constant drought and to see the damage from Emerald Ash Borer.
I had a blast at the Denver Botanic Gardens and learned some great information regarding Xeric gardens, or water conserving gardens. I also saw some great new plants to try in the annual and perennial trial gardens at Colorado State University, but my favorite part of this professional development trip was visiting with the Extension faculty from Colorado State University about Emerald Ash Borer (EAB).
Boulder, Colorado is the first and only county to have found EAB in Colorado. We were informed of the steps that Boulder County and the Colorado State Department of Agriculture took to help reduce the spread of this invasive insect into other counties and towns in Colorado. We were then taken to a site with massive damage from EAB to see what this insect does to the trees. It was good for me to see it live for myself to know what to look for in Nebraska.
As of today, Emerald Ash Borer has not been found in Nebraska, but we should be on the lookout for it as it has been found in Iowa, Missouri, Kansas, and Colorado. EAB is a small, metallic green, wood-boring insect that is invasive. It came to the United States via wood-packing materials from China and was first discovered in Michigan in 2002. Because EAB is an invasive insect, it has no natural predators to keep the population in check.
Emerald Ash Borer attacks healthy and stressed true ash trees, it does not attack mountain ash which is not a true ash species. EAB larvae feed on the inner bark of the ash trees, which causes a disruption of the flow of water and nutrients throughout the tree. If you have an ash tree that exhibits any of these signs, please let me know so we can check it out to ensure EAB does not get into or go unnoticed in Nebraska.
The damage from EAB can show up in your ash tree as
- Top dieback
- Sprouting at the base of the tree
- Increased woodpecker damage
- Larval galleries under the bark of the tree
- 1/8 inch D-shaped exit hole
- Bark cracks
- Reduced size of the leaves still on the tree
Insecticide treatments are available for Emerald Ash Borer but are not recommended until the insect has been confirmed within 15 miles of your trees. The insecticides used can be applied either via a soil drench or trunk injection. Trunk injections are only to be done by trained professionals. Insecticide treatment efficacy depends on the size of the tree, the insecticide used and how it is applied, and the damage the tree has already acquired. If it is a high value ash tree, treatments can be effective, but are not feasible on a large quantity of trees.