June 20, 2018
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Fungal infections causing damage to NE white pines

By From Staff Reports, Special to the BDN

AUGUSTA, Maine — New England’s white pine trees are raining needles because of widespread fungal infection, the result of several unusually wet spring and summer seasons.

While older needles are quickly yellowing and dropping from branches in droves, the Maine Forest Service’s Division of Forest Health and Monitoring remains hopeful the trees will not die and that drier weather this year will leave new growth untouched.

“New growth may not yet be infected,” William Ostrofsky, a forest pathologist with the Maine Forest Service, said in a statement. “We’re hoping that this current year’s needles won’t be affected and will remain on the trees as long as they should.”

A pair of fungi, Canavirgella banfieldii and Mycosphaerella dearnessii, seem to be the culprits, but the former is much more prevalent in Maine. Commonly known as white pine needle cast, Canavirgella infects 1-year-old needles that began growing the previous year, causing them first to turn yellow and brown before prematurely falling from the tree.

Despite their sickly appearance, it seems the fungi have not raised the mortality rate of Maine’s 1.4 million acres of white pines. The damage caused by the disease is readily apparent in the state’s southern and western counties, where the highest concentration of white pines can be found. However, the problem can be seen statewide, Ostrofsky said Tuesday.

No fungicide has been developed to treat the infection since it has not caused serious concern in the past.

“We’ve never before documented this level of this disease,” Ostrofsky said. “We’ve never had four to five years of back-to-back high rain levels.”

According to the National Weather Service, some areas of Maine received 4 to 5 inches of rain over a period of three days in June 2009. Such extensive rainfall creates the perfect conditions for fungi to incubate, which explains why these diseases only recently have become a noticeable problem. With any luck, this year’s drier weather will continue this summer, leaving new growth untouched by disease, according to Ostrofsky.

“The diseases probably have been here, but they just develop when weather conditions are right,” he said. “When weather conditions are just right, we see a flare-up.”

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