As a Minneapolis resident and an arborist with 30 years in the tree care profession, I want to offer some deeper context to the issues raised in Cam Gordon’s Nov. 8 article on emerald ash borer and insecticide treatments.
I ask fellow community members not to assume ill intent of arborists, who are and have always been environmental allies. We are most often called out to try to solve preventable tree problems after it is too late. There is a lot of pressure right now from people with ash trees to try to save them, when the window of opportunity closed several years ago on many of these trees.
The Twin Cities metro area has had greater success than any other city in the country in preserving ash canopy since the arrival of EAB. This is in part due to the responsible and selective use of pesticides to protect ash trees – not perpetually, but as a means to reduce population pressure and as a bridging strategy toward removal and replacement.
We all get to decide what our risk tolerance will be in a given situation. Even Toyota Prius drivers accept the use of some fossil fuel to get themselves down the road. We get to decide what kind of urban forest we will have as a community. When use of pesticides is taken off the table, removal and replacement is the only option for ash trees. The longer the delay in either choice (protection or removal and replacement), the more difficult and dangerous it becomes to remove an infested ash tree. This is due to the succession of fungi that invade the galleries formed by the borer, making the wood lose almost all its strength and stability. Infested ash trees are more expensive to remove because they require more time and specialized equipment to get the job done while reducing risk to workers.
To sum it up, I have three requests for those in the community:
Look up the work done by Dr. Reed Johnson of Ohio State University for in-depth research about the exposure of pollinators to emamectin benzoate through ash pollen.
Don’t assume ill intent of arborists. They got into their careers because they care about the environment. Our profession is dangerous, and we strive to care for trees and our workers.
Take care of your trees proactively! Water them, mulch them, and get regular pruning done. We have had three years of drought, and even tolerant species are getting stressed and dying. If you want to avoid insecticides, reduce stress on your trees any way you can.
International Society of Arboriculture Board Certified Master Arborist MN 0158B
Rainbow Tree Company