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Pine Decline: Fungal Blight Threatens Crucial Tree in Timber Industry

6 min read

Professor Michael Blazier began planting trees as a Boy Scout, switched his specialty to get out of the lab and into the woods, and now is battling a fungal threat to the most valuable species in Arkansas’ $6.5 billion-a-year timber industry.

It’s the loblolly pine, the “bread and butter” of Southern logging.

As director of the Arkansas Forest Resources Center, Blazier is inspecting trees and huddling with colleagues to investigate why a fungal disease called brown spot needle blight is stressing more pines, and he’s also devising ways to mitigate it.

Once little more than a nuisance in loblollies, the blight was found on the Gulf Coast in other evergreens. But it has spread and is attacking stands of loblollies in Arkansas, said Blazier, dean of the College of Forestry, Agriculture & Natural Resources at the University of Arkansas at Monticello.

 

“It was really a nonissue for loblolly pines, but for some reason, its behavior has changed,” Blazier said. “It’s never been a lethal disease, but now it has become recurrent and heavy enough that we’re seeing some of them die. And even if it doesn’t kill the trees, it takes off a lot of needles and the trees aren’t growing as fast. The timber isn’t gaining value as fast as it normally would.”

The disease is also nipping away at the beauty of the state’s vast evergreen forests, he said. Arkansas has 19 million acres of forest covering 53.4% of the land. Arkansas’ timber industry has an annual payroll of $1.7 billion, according to the Department of Commerce.

Pine trees are evergreen because each year they sprout a new set of needles while retaining the needles produced the previous year. The blight has now jumped from the old to the new needles in some trees. Brown spots appear on needles, then yellow bands, and needles eventually go brown and slough off.

Some infested trees are nearly bare. As one forester put it, you end up with something that looks like a Charlie Brown Christmas tree.

Blazier attended a multistate gathering of forest specialists tackling the problem this month at Auburn University. Several samples gathered by Blazier and fellow UAM forestry Professor Matthew Pelkki tested positive for brown spot needle blight at Auburn, and they suspect that several years of rainier-than-average weather energized the fungus, Mycosphaerella dearnessii.

“The level of mortality we’re seeing isn’t excessive, like we have seen in the worst beetle infestations, but it’s a chipping away at the forest, and it’s not something we want to take lying down,” Blazier said.

“We’ve had massive amounts more rain than usual in the winter and spring for several years in a row,” he added. “When it’s wet like that, plants grow really well, but the agents that kill plants grow well, too.” The airborne fungus spores thrive in sustained wet conditions, but much remains to be learned.

“Another suspicion is that there may be some soil nutrient component to it, but it’s very early to determine that. There may be some soil formations where this blight tends to be more prevalent.”

Brown spot needle blight in itself is not killing a lot of trees, said Vic Ford, associate vice president of agriculture and natural resources for the Arkansas Cooperative Extension Service, part of the University of Arkansas System Division of Agriculture.

“Mortality is a function of a lot of things,” Ford said, noting that some locations with dying trees have the blight, but some don’t.

 

Compounding factors add up, and if the blight persists long enough, trees can wither away. Blazier’s chemical diagnostics have also found cases of another disease, needle cast. Tests for the presence of herbicides were inconclusive.

Small Landowners Worried

Larry Boccarossa, executive director of the Arkansas Timber Producers Association, told Arkansas Business that he’s heard it may take a year to be certain about what is killing stands of loblolly pines. Some timber producers believe it’s farm chemicals or the needle blight, or a combination of factors.

“This could potentially be a big problem, especially for small private landowners,” Boccarossa said. “They may have an investment of 100 acres or more, but they’ve been hit by this,” and losing even a few stands of trees would take a real toll, he said. “I was at a meeting down in Hamburg and talked to some individuals that have this on their land. They are very concerned.”

Blazier said the loblolly is “really the bread and butter of the forestry industry across the Southeast U.S., and Arkansas is no exception.”

 

Some trees infested with brown spot needle blight eventually lose many of their needles, though most aren’t actually dead. They may be revived.
Some trees infested with brown spot needle blight eventually lose many of their needles, though most aren’t actually dead. They may be revived. (Lon Tegels/Arkansas Forest Resources Center)

 

Before, though, foresters had little need to fight the blight because it wasn’t an economic threat. Now serious work is underway.

“We’re about to mount our next round of sampling,” Blazier said. “At a recent fundraising event with loggers, one of them told me I needed to take a ride with him down to Hamburg, where one stand that seemed to be looking better was now looking worse.”

Blazier and his team meet every two weeks with representatives of the Forestry Division of the state Department of Agriculture, the Arkansas Forestry Association and the Extension Service. “We share data and join forces to develop faster responses. Other states have found it’s important to have cooperative arrangements to cope with these kinds of things.”

One simple weapon against the fungus is prescribed fire, controlled burns on the ground that destroy the infected needles and kill the spores.

“This hasn’t been scientifically proven, but we have anecdotal evidence that controlled fires have the potential to reduce infection,” Blazier said. “Another line of research is studying some fungicides that might be useful.”

 

Timber’s Value

One problem with that approach is that the blight tends to start at the lower part of the crown of the tree and move upward, making effective aerial spraying difficult. Blazier is also looking at forest management techniques in areas unaffected by the blight.

Blazier said loblolly pines are impressive trees, maturing at about 30 years and reaching average heights of 80 to 90 feet with trunks 20 inches in diameter.

“I was a Boy Scout and before that a Cub Scout,” Blazier said, explaining how he came to study trees. “Every year we would go out and plant trees in areas of the Scout Ranch. There were a couple of foresters that would make a big stewpot to keep us warm and energized.”

As a chemistry major at Louisiana Tech, he remembered those times and switched his field to forestry. Then came graduate school at Oklahoma State and a master’s in forest ecophysiology, “a $25 word for silviculture and soil.” After getting his doctorate in Stillwater, he spent years teaching at Louisiana State University, then became the dean at Monticello in July 2021.

Blazier knew how important forestry was to Arkansas, but he learned just recently from studies by his own college that Arkansas’ 4th Congressional District ranks second in the country in terms of the contribution forestry makes to the local economy.

“We’re heavily forested, and we get a lot of value out of our forests,” he said. “We have a vibrant ecotourism in hunting and camping and hiking, and our forests are the underpinning of all that. It’s a major responsibility to protect them.”

 

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