Leaf disease is moving into the region
By Mike Lynch
Beech trees in the Adirondacks are facing a new threat: Beech leaf disease.
First spotted in Ohio in 2012, the disease has spread throughout much of western New York, Long Island, and lower Hudson Valley. Its origins are unknown.
In June, the state Department of Environmental Conservation confirmed its presence in the southwestern Adirondacks, northwest of Stratford in Herkimer County.
The disease can kill adult trees in 6 to 10 years and younger ones in just a few years. It is at least the second disease to impact the species. Beech bark disease has been killing mature beech trees for decades.
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“Unfortunately, the forecast does not look good for beech trees in North America,” said Maria MoskaLee, a forest health specialist with the state Department of Environmental Conservation, during a webinar on the disease in September.
American beech trees, sugar maples and yellow birch trees are the most common tree species in northern hardwood forests, which make up more than 50 percent of forests in the Adirondack region, according to SUNY ESF.
The tree’s nuts are an important source of food for more than 40 species of wildlife, including deer, squirrels, and birds. Researchers have found the nut’s high protein and fat content are especially important for black bear reproduction and survival.
“Loss of beach would cause changes in forest structure that would affect the entire ecosystem,” MoskaLee said.
DEC first started hearing about symptoms of beech leaf disease in 2017, then started tracking it in 2018, MoskaLee said. The first reports came from the southwestern part of the state.
“Each year since we’ve seen a significant expansion of the disease range,” MoskaLee said. “So far this year, we have found beach leaf disease in 15 new counties.”
Close to 40 New York counties have reported cases of beech leaf disease. It not only impacts native American beech trees, but imported varieties.
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Because the disease was recently discovered in the U.S., its biology and vectors aren’t well understood, MoskaLee said. Some research has shown that the nematode worm, Litylenchus crenatae mccannii, plays a role in spreading the disease, but it’s unknown if it is the sole cause of the damage or if the disease is associated with another pathogen, such as a fungus, bacteria or virus.
It’s also unclear how the disease is spreading from place to place. Some theories have focused on birds and humans spreading it.
But scientists are finding that it moves quickly.
In a study of the disease at Kennedy State Forest in Cortland County, DEC forest health scientists found it expanded from about one acre with 190 trees in 2020 to about 4.5 acres with 940 trees the next year. In 2022, it has ballooned to 15 acres. Plus, it’s spread to isolated forested areas about a mile or so away.
Although there is no known management strategy to stop the spread of the disease, some trees have shown natural resistance. In addition, pesticides are being studied to slow the spread.
Symptoms of this disease can be found on the leaves and are most visible from the underside when held up to the light. Infected leaves may be darkened, have stripes, and be thicker than usual.
Because American beech trees have already been hit hard by the bark disease, forestry consultant Tim Burpoe said if this additional disease did cause the demise of beech trees, it wouldn’t make a “big hole” in the forest product industry. Mature trees are often hollow and aren’t used for high-quality products. Instead, the wood is used for items such as pallets.
“It doesn’t grow up to be a real good forest product,” said Burpoe, who has worked in the industry for several decades.
However, he did say beech does make good paper and firewood.
The September webinar on the disease was hosted by the Adirondack Park Invasive Plant Program and was intended as a training session for volunteers. The volunteers are being asked to look for symptoms of the disease on their outdoor excursions, photograph the evidence, and file reports on the Imap Invasives app, a tool used by land managers and scientists to track the spread of invasive species.
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