Beech leaf disease spreads across the States

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SUSCEPTIBLE: American beech leaf disease. (Photo: University of Ohio)

AMERICAN beech trees are dying and nobody knows why, raising the fear whatever it is could spread worldwide.

Ohio State University researchers are looking into the cause of beech leaf disease, which was first found in Lake County on the Lake Erie shoreline in 2012 and has since spread to nine other counties in Ohio, eight in Pennsylvania, one in New York and five in Ontario.

The disease was first reported on American beech trees, the only beech trees native to North America, but similar symptoms have been found on European and Oriental beech trees in nurseries in Lake County.

“That suggests other species are susceptible,” plant pathology professor Enrico Bonello says.

“There’s potential for the disease to spread worldwide in the northern hemisphere.”

Bonello says young trees seem to be particularly susceptible to the disease, which initially causes dark stripes to appear on leaves, then deforms the leaves. Eventually the disease can kill the trees.

“There’s no similar forest tree disease that we are aware of anywhere,” Bonello says.

Doctoral graduate student Carrie Ewing is comparing the genes of microorganisms present in leaves that have symptoms of beech tree disease and those that do not, hoping to identify the microorganisms that are uniquely associated with beech leaf disease.

She’s trying to determine whether the mystery microorganisms causing the disease are viruses, fungi, bacteria, phytoplasmas or nematodes. Phytoplasmas are bacteria without cell walls. Nematodes are microscopic worms.

“We are comparing huge amounts of data, kind of a shotgun approach,” Bonello says. “It’s like trying to find a needle in a haystack by comparing various haystacks.”


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