Written by: John Wayne Farber, Board Certified Master Arborist (BCMA) WI-0877B, Certified Treecare Safety Professional 01462
What is the future of ash trees? Will Emerald Ash Borer (EAB) ever go away? These are good questions as we head into a third decade of the EAB crisis.
Several studies have some preliminary evidence of possible genetic resistance in the remaining ash tree populations. It seems some trees can survive (not thrive), at least in low-density EAB populations. This offers hope that perhaps if we look hard enough and select trees that show resistance, through breeding practices we might be able to keep native genomes. The more practical way we may be able to continue to enjoy ash trees is through hybridizing native trees with ash trees that survived in areas of Asia where EAB occurs naturally. Through lessons learned from the elm trees, we have become good at creating a tree that is mostly native with a hybridized trait that makes it resistant to a particular pest. All this being said, trees take a long time to grow, different age and size classes respond differently to EAB pressure. We are a long way away from ash-lined streets again.
A quick lesson in the environmental biology concept of carrying capacity (K) may hold the key to this invasive pest’s future. Carrying capacity is the concept in which an environment determines the maximum size of any population. Some major factors that contribute to this are food availability, suitable shelter, and level of predation. Think of EAB like a fire. If there is fuel for the fire (lots of healthy ash trees), the fire will rage and consume its fuel (food) source. But after the fire has burned an area it doesn’t have the fuel required to burn it again, at least immediately. EAB is reacting the same way. When EAB was first introduced to the U.S., it had massive capacity to support it – an all-you-can-eat ash buffet. But as EAB eats its available food and shelter, the environment can’t continue to possibly support the same number, so the population must decrease in response.
We are speeding its demise with increased predation pressure (parasitoid wasps), more diversity (less ash trees), keeping trees treated, and creating resistant ash trees (less food). As long as edible ash trees exist, so will the little green pest. The future of ash trees may look different from what we are accustomed to, but we will likely still see and recognize the tree we have grown to love into the future.
We have been working with many of our customers for years to preserve their ash trees! The treatments do work: Research shows that emamectin benzoate treatment has a 99% EAB mortality rate, even in ash trees that are in close proximity to untreated trees. Watch this short video on how we perform EAB treatments.
Get in touch with us today if you'd like to request a tree inspection in your yard by one of Hoppe's certified arborists.