BETHEL — Maine’s state tree, the Eastern white pine, is looking rather ragged across Western Maine this month.

The trees are primarily suffering from overwatering by Mother Nature for the past eight years. That’s allowed a suite of fungi to flourish and attack.

The white pine needle disease epidemic, as it’s called, is turning the needles yellow and brown this month before causing the trees to prematurely shed or “cast” their needles. This defoliation, in turn, can be fatal for thin and weak trees, William Ostrofsky, Maine’s forest pathologist, said Wednesday in Augusta.

“White pine is Maine’s state tree and a pretty significant timber crop,” he said. “It’s the dominant pine in Maine, and the lower half of the state is where the core white pine industry is located.

“This week, we’re starting to see mortality if the white pine trees are in the understory and shaded out or at poor sites on lake shores and at camp areas,” he said.

Normally white pine trees hold their needles for two years.

Pine tree needles use photosynthesis to make food — sugars and starches — that the tree needs for life and growth.

“White pine trees affected by the needle disease work at 50 percent capacity, so it’s difficult to maintain growth,” Ostrofsky said. “It’s not fully the fault of needle cast.”

Maine Department of Agriculture, Conservation and Forestry officials have received many calls recently regarding this extensive early drop of white pine needles.

Callers have stressed that the white pine crowns of affected trees have turned from the dull winter green to a yellow-straw color, and then quickly to tan and brown, according to an informational bulletin from the department released Tuesday.

Heavy rains then washed off nearly all of the affected needles, leaving behind current-season needles and thin crowns. With many trees now having only the current-season needles left to photosynthesize, people are concerned, Ostrofsky said.

“I’ve been getting a lot of calls on it, because this is the time that it gets to be evident,” Patty Cormier, Maine Forest Service district forester, said Wednesday in Farmington. Her district is Franklin and Somerset counties.

Cormier said she’s been receiving at least two calls a week from people in both counties who are concerned about the discoloration and defoliation. That’s more calls than usual.

“I got calls because the trees looked so bad,” she said. “People thought that some insect was killing things.”

The Maine Forest Service has been tracking white pine needle disease since 2007.

“We think it’s largely weather-driven,” Ostrofsky said.

The epidemic has been happening in Maine and across New England and New York for at least eight consecutive years. He said Maine experienced a wet spring and summer in 2006 and 2007, and then in 2009, it rained all summer. Heavy defoliation followed in 2010.

“I hope there will be a break in the weather pattern or something else where this will subside,” Ostrofsky said.

Bethel was particularly hard hit this summer and along the Androscoggin River, he said. To view the damage, drive along Route 2 between Rumford and Bethel.

Cormier said diseased white pine trees can also be seen while traveling on Route 201 toward Bingham.

“It’s all along the road and it looks awful,” she said.

While the above-average spring and summer precipitation patterns for the past eight years are the main culprit, the unseasonably wet weather is also the primary factor that is allowing three needle-cast fungi to grow on and infect white pine needles.

The primary fungus is called “brown spot needle blight,” or Lecanosticta acicola.

“Wet weather allows its spores to germinate on the needles and infection occurs,” Ostrofsky said.

Trees affected by brown spot probably will shed their needles the following year.

The other two fungi are Canavirgella banfieldii, which he said affects 1 to 2 percent of trees, and Bifusella linearis.

“I’ve seen all three take advantage of needles,” Ostrofsky said.

He said the forest service is also starting to see a canker disease in white pine trees that’s caused by another fungus.

Fungi infect needles early in spring and develop through the needles during summer and fall. The following year, when the weather warms, the symptoms on the infected year-old needles first appear during early to mid-June.

The progress from symptom development through needle casting occurs over a very short period of time — usually about three or four weeks. The symptoms appear as a rapid flare-up of needle yellowing and casting, which has occurred throughout Maine in the past two weeks, Cormier said.

This year, trees continue to show weakening due to the stress caused by the reduction in foliage and photosynthetic efficiency, Ostrofsky said.

What can be done?

State foresters are collaborating with neighboring states and with the U.S. Forest Service to determine the scope of the problem and identify solutions.

Ostrofsky said research is underway at the University of New Hampshire because of growth loss in white pine trees in that state.

In Maine, a survey of damaged trees is underway. Results will be compared with defoliation estimates from previous years.

Early indications are that the severity of disease is similar to that in past years, but that the long-term effect of many consecutive years of the loss of the one-year-old needles has weakened some trees to the point where mortality is now occurring, Ostrofsky said.

Other secondary insect and disease problems also appeared in many stands where sustained and severe damage from the needle disease complex has occurred. However, these effects are not yet well-understood.

It appears that, for the foreseeable future, white pine will be another threatened resource unless the needle disease epidemic abates, either from a break in the weather and moisture patterns or from some other as yet unknown reason, Ostrofsky said.

Control or management recommendations are limited, but state foresters urge caution before conducting thinning operations. Landowners should consult with a professional before such operations.

Ostrofsky and Cormier said repeated defoliations have already stressed the affected trees.

“The important thing if the trees look like they’re in a relatively weakened state, it’s best not to add additional stressors, so we don’t recommend people go in and thin the lot out,” Ostrofsky said.

“On the flip side, if the trees are really debilitated and the woodlot owner is worried about losing the trees, take all of the harvestable trees, because the remaining trees won’t survive,” he said.

“In the spring, you don’t want to thin them, because it will spread the (fungi) spores,” Cormier said.

For yard and ornamental white pine trees, Ostrofsky recommends hiring an arborist to apply fungicides. “That will take care of it,” he said. “But it’s not controllable in the woodlands.”

As this season progresses, current-season foliage will develop that will help to “mask” the thin appearance of the crowns.

Heavily-infected stands and trees in stands where mortality is believed to be the result of needle diseases may be salvaged.

“Many trees will come right out of it,” Cormier said. “If they’re strong enough, they will be fine.”

She said she doesn’t believe the disease is enough of a problem yet to affect the white pine timber industry.

Cormier said the problem is happening along roadsides and more urban settings.

“I haven’t seen it deep in woodland settings, but that doesn’t mean it’s not there,” she said. “It’s weather dependent. There’s not all that much that we have control of.”

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Who to contact

Woodland owners are encouraged to contact their licensed forester to help assess the actual impact of the blight on their white pine woods. For yard and ornamental trees, contact a licensed arborist. If you need help finding a resource professional, contact the Maine Forest Service at 1-800-367-0223 (in state) or (207) 287-2791.

For more information about the Maine Department of Agriculture, Conservation and Forestry, visit www.maine.gov/dacf.


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