Emerald ash borer: You can help save Vermont’s ash trees

Learning about the insect is the first step

On a perfect summer day, 40 foresters gathered on woodland in Rupert, Vermont. They were here to learn more about managing forests with ash trees, given the threat of emerald ash borer. The larvae of this invasive beetle chew tunnels under the bark; this cuts off water and nutrition and usually kills the tree.

Forester Alan Calfee hosted the workshop on land he conserved with the Vermont Land Trust. He helps manage around 25,000 acres on parcels ranging from 20 acres to 5,000. Emerald ash borer hadn’t yet been found in these lands, but people are asking him about it.

“The workshop was a bit of an awakening for me,” he reflects. “It really hit me that this pest is here. We have to start managing the forests for emerald ash borer now.”

Why we shouldn't cut all ash trees now

Vermont is the 31st state with confirmed EAB so it might benefit from what other states have learned.

“Just recently, people assumed emerald ash borer would kill nearly every ash tree,” says VLT forester Pieter van Loon. “But new research suggests there’s more variability.” While some places have seen almost no survival, 75 percent of white ash survived in parts of Michigan, which has had emerald ash borer for 17 years. No one knows why. “The take-away is don’t cut all your ash, because some may live.”

“We have to do whatever we can to create an understory of ash,” Alan adds, “so that if the bug takes out the overstory we have the greatest chance of getting new trees to seed-bearing age.”

Female ash trees are critical to the tree's survival

Alan advises people to be aware that ash trees are either male or female, and while a single female tree needs several male trees nearby, it is also important to maintain large, healthy female trees “so there are seeds for the future.”

This picture shows a stand of ash being blown around by a brisk south wind. There are lots of red and yellowish clumps of seeds on the ash in the center of the photo. Almost all the rest have no seeds. The center tree is female and they are surrounded by males.

“Turns out, the recommended ratio is 6-12 male trees left for every female,” explains Pieter. “This is to be sure there is enough pollen to blow around and fertilize the female flowers. If your next timber sale is more than a year away and you want to retain some ash trees with the goal of getting some regeneration, you might want to go out when there are seeds and mark the males and females.”

“It’s about saving a species”

Alan sees hope in owners of conserved land. “The land trust has a population of forest owners who think long-term and can make a difference.” He adds, “It’s about saving a species.”