I recently stumbled into an informative, hour-long webinar from Purdue University Extension, drawn in by updated information on how we can fight the emerald ash borer. The day was cold and windy, and yes, I have an ash tree in my yard.
As a brief refresher, EAB was first detected in Indiana in 2002. Since then, it has killed tens of thousands of ash trees (Fraxinus spp.), moving quickly throughout the Midwest and elsewhere, spread mostly by contaminated firewood.
Tiny, metallic green beetles feed on the leaves and lay eggs in the bark. The eggs hatch and the larvae bore into the tree. The larvae destroy the layers that move water and other nutrients to branches, limbs and leaves, eventually starving the tree to death.
Initially, experts recommended treating ash trees or cutting them down, whether infested or not. The result, healthy but threatened trees were removed because annual treatment was expensive for municipalities, park systems and government entities. Homeowners were told to treat ash trees if they were important in the landscape and to take down others.
Researchers have had more than 17 years to study this exotic invasive insect from Asia and have new recommendations and a warning.
- Monitoring all species of ash trees in your landscape, neighborhood or public areas is critical. Woodpeckers at the top of a tree may be an important indicator of trouble.
- The earlier you detect thinning at the top of an ash tree, called canopy loss, the better your chances it will recover with treatment. Trees with up to 30 percent canopy damage can be treated and likely saved.
- Three-year protection is a reality. Rather than annual or every two-year insecticide applications, they may be needed only every three years. These insecticides are injected into the trunk of the tree, but are not available to homeowners. Certified pesticide applicators or arborists need to apply these chemicals.
- Cost of treatment is competitive with taking an ash tree down and replanting another species of tree. An older also tree has more value in a landscape.
- Of course, you always want to work with a certified arborist (treesaregood.org). These highly trained professionals carry proper insurance, licenses and other certifications to do the job, protecting themselves, you and your property. Avoid what we call trunk-slammers, the folks who walk the neighborhood offering to trim your trees.
- Researchers are exploring parasitic wasps as a possible control.
- Researchers are studying ash trees that have survived an EAB infestation to see if they have some type natural resistance.
He said we’ll never get rid of EAB, but that it’s possible to knock it back. Also, he said, don’t replant ash trees with more ash trees.
Dead ash trees are a threat to public health, Cliff Sadof said in the video. Research indicates the trees become weak and hazardous as soon as two years after EAB infestation. “They become incredibly brittle,” the Purdue Extension entomologist said.
Branches and limbs fall during wind, heavy rains and other environmental influences, even vibrations. But their brittleness heightens the hazard for arborists who take the tree down. “I can’t emphasize how scary it is,” Sadof said. “We don’t have to have ash trees that die,” with proper treatment and management.
More EAB resources
- Emerald Ash Borer Management
- Practical EAB Management Video: A 2019 Update
- Emerald Ash Borer Information Network