Disease Causing Massive Damage To Trees Throughout CT: Scientists

CONNECTICUT — Beech leaf disease, which can kill trees within a few years of infestation, is now widespread and prevalent in Connecticut.

The disease is running rampant on American beech trees throughout Fairfield, New Haven, Middlesex and New London Counties. Less severely, it appears to be spreading into Litchfield, Tolland and Windham Counties, according to researchers at the Connecticut Agricultural Experiment Station. There have been no confirmed observations yet in Hartford County.

The disease is caused by nematodes, a word which covers a "phylum" of up to a million different species found in every known ecosystem. The disease was first seen in North America in Ohio in 2012, but the nematode involved was not identified until later, and not even proven to be the cause until 2020. It has also had its way with trees in Pennsylvania, New York, and Ontario, Canada.

The younger trees are more likely to succumb to the disease once infected, according to Robert Marra, a scientist in the Department of Plant Pathology and Ecology at the Connecticut Agricultural Experiment Station.

"And that seems to be, based on the data from Ohio, in 5-7 years," Marra said.

Detection of BLD is best done from below, looking up at the beech tree's canopy. The disease is characterized by dark striping between leaf veins (pictured above). The symptom appears when leaves form in the spring.

But the disease has kicked into high gear this year, and the symptoms have followed suit. Hikers can now expect to see aborted leaf enlargement, cupping, browning and yellowing of foliage; branch and tip dieback; and in some cases, premature leaf drop.

The infestation is so grand and pervasive, Marra said, that "It seems as though — at least in the lower four counties of Connecticut — that somebody just sprayed nematodes into the trees!"

Worse still, it's not just hammering the saplings anymore.

"We are seeing mature beeches with large sections of their canopies already infested with nematodes," the botanist told Patch,

Why? That's still a mystery. Nematodes can't fly, they have no migration patterns.

"Nematodes are moving," Marra said, "but they are not moving themselves. Birds? Squirrels? Spider mites? But we have no direct evidence of any of these things."

Marra said that the BLD symptoms being reported this year are also very different from what he saw last year in Connecticut. He speculates the root cause may be the very dry summer and spring the state has most recently experienced.

Although more of the older tree are being affected, saplings aren't being spared this year. In fact, they're literally dying on the vine. "Some of these saplings, the youngest recruits, are, if not completely defoliated, close to it. Their leaves have already dropped off."

If you have a beech tree on your property that's getting worked over by nematodes, Marra suggests contacting a local arborist. If the damage is on a tree in a town park or along a public roadway, contact your town tree warden. The Connecticut Tree Wardens Association recommends contacting your town first to find out if they employ a tree warden.

But don't get your hopes up. Marra compared the current battle between beech trees and nematodes with the one between emerald ash borers and ash trees.

"And we've pretty much lost ash trees," he said.