There’s a new sickness in New England, and it’s killing some of the region’s biggest native trees.
Beech leaf disease is a condition caused by microscopic worms (Litylenchus crenatae) that—as the name suggests—invade the leaves of a beech tree, erode the foliage and eventually kill the whole tree.
“This tree is in the very early stages of getting that disease, and if it’s a typical pattern, this will have almost all of its leaves killed next year,” Dr. Richard Primack, a biology professor at Boston University specializing in plant life and climate, said as he stood under a gigantic beech tree in a yard in Newton Centre. “And the tree will likely die in about three-to-four years.”
At a time when water tables are rising, the climate is heating and the Garden City is struggling to preserve its trees, a tree plague is the stuff of nightmares.
Worming their way in
Beech trees are native to Europe, Asia and North America, particularly the Northeastern United States and southeastern Canada. They tend to have smooth bark and can grow up to around 100 feet tall.
Their size makes them great at cleaning the air around them and soaking up groundwater beneath them.
In 2012, a new disease infecting beech trees was discovered in Ohio, and the blight was found in Massachusetts in 2020, according to the state’s Department of Conservation.
There are lots of conditions that can kill leaves, but beech leaf disease has a very distinct symptom: checkered pattern of rot that spans the leaf.
“And it’s caused by a nematode, a microscopic worm that you can’t see with your eye,” Primack explained.
The microscopic worms travel in a variety of ways, Primack said, primarily carried by the wind and by birds from branch to branch.
Primack knows the owner of the property where that enormous diseased beech stands, and he said he told her about the disease and she’s having an arborist check it out.
“This is a magnificent tree. This tree is probably a hundred years old,” Primack said. “It has this fantastic branching pattern, it shades the house beautifully, and this tree likely will be dead in about three years.”
Walking into nearby Webster Woods, Primack noted several trees bearing those trademark checkered wilting leaves.
“I thought it was frost damage when I first saw it, but it’s not frost damage—it’s the beech leaf disease,” Primack said as he pointed out a row of diseased branches, before noting a toad camouflaged in the fallen leaves below.
No way to quarantine
Marc Welch, Newton’s director of urban forestry, said the city isn’t addressing beech leaf disease because there’s really no way to do so.
For starters, the city doesn’t treat trees on private property or in state conservation land.
“On our regular park trees, street trees, stuff that we manage, we don’t have a lot of beech trees,” Welch said.
And even if the city could manage all of the trees in Newton, there’s no way to make birds and other animals “social distance” to avoid spreading the parasites from tree to tree.
Welch recommends that property owners who are concerned about beech leaf disease contact a certified arborist, like the aforementioned homeowner in Newton Centre plans to do.
“That’s good for all types of trees and for all types of issues, just having someone managing the trees on your property who can view them, check them and monitor them for potential problems,” Welch said. “Because those private companies deal with treating various types of trees for various types of reasons, they will be able to recognize if in fact their beech tree does have beech leaf disease or any number of other maladies that can affect beech.”
Chemical treatments, like the disease itself, are still relatively new and long-term effects are unknown.
For now, Welch said, it’s all about watching and waiting to see how the disease evolves.
“As history goes, there are diseases, insects and other things that—when they’re first discovered—they’re very impactful but over time, for a variety of reasons, they may be less impactful,” Welch explained. “And that could be because there are other insects that help control them, or there is a treatment method, or maybe there was a set of weather conditions over a few years that caused the population to get particularly bad. “So sometimes it can work its way out, or it can be devastating and be here for a very long time without a lot of good options to treat it,” Welch said.