UMaine Student Battles Beech Bark Disease
Contact: Matt Kasson (207) 581-2897; David Munson (207) 581-3777
ORONO, Maine – Matt Kasson, a master’s degree candidate in UMaine’s newly formed School of Forest Resources, is working to assess the future of Maine’s beech trees, having made it his mission to understand the disease that is rapidly turning one of the state’s top trees into so much cordwood. Kasson, along with the help of a few dedicated undergrads, has bushwhacked his way to beech stands from more than twenty townships, drilling core sections and gathering bark samples that he hopes will lead to new information that could help explain the deadly blend of afflictions that cause beech bark disease.
“What we’re seeing is not just a pathogen, it’s a complex,” said Kasson as he arranged a set of crimson-colored cultures in an incubator in the lab. “There are a number of factors that can lead to the same result. What we are trying to do is determine what factors contribute to high mortality in these stands so that we can better understand how this disease is affecting the trees and the forest.”
Kasson has collected more than 2,200 tree cores — pencil-sized cylinders of wood that provide a record of tree growth from its days as a sapling to its most recent annual ring — that he hopes will provide important clues to how the disease kills. By comparing beech cores to cores taken from other tree species unaffected by the disease, Kasson may be able to determine what environmental conditions contribute to both the spread of beech bark disease and the likelihood that it will kill its host.
Pathogens causing beech bark disease were introduced to North America in the 1890’s, arriving in Nova Scotia, Canada in a shipment of contaminated beech seedlings from England. From there, the pathogens spread west and south, reaching Maine’s coastal region by the 1930’s. The primary pathogen is an exotic scale insect, Cryptococcus fagisuga, which provides access channels into the host tree’s tissues for the second pathogen, an invading fungus.
“The scale weakens the tree, but the fungus kills it,” said Kasson. “The roots usually survive, sending up dense thickets of young shoots that have no resistance to the pathogens.”
Strangely, while one of fungi known to help cause the disease was introduced from Europe: Neonectria faginata, the other, Neonectria ditissima, is a native of North America just like the beech.
Kasson is examining the unique relationship between the two fungi to see how their interaction may affect the occurrence and expression of the disease across the landscape. Initial observations suggest that the foreign species may be replacing the native fungus in the disease complex.
Kasson hopes that what he learns through his research can be used to save the surviving beech trees in Maine and across the country.
“The fact that beech bark disease came into Maine first means we are on the front lines,” said Kasson. “We need to find out as much as we can now. It’s moving into Pennsylvania, Virginia, Michigan and elsewhere, and what we have here may just be a preview of coming attractions.”
In addition to being an important tree ecologically in Maine, it is economically important as well, providing high-density wood for use as flooring, furniture, plywood and fuel.