A foliage disease epidemic that killed shore pines near 10 Mile and other areas around Haines appears to have subsided, according to a U.S. Forest Service pathologist who visited here last week.

An agency website page on the disease in Haines and Skagway called the outbreaks “severe” and “unprecedented.”

A Forest Service map shows areas affected straddling Takshanuk Ridge between 8 Mile and 30 Mile and around the upper Chilkat River near the Canada border.

“Most of the trees look like they survived and are recovering,” Robin Mulvey said in an interview Monday. “We’re not seeing fruiting structures of the fungus, which is one of the signs you look for. Most of the trees we saw had two years’ worth of needles. It’s promising.”

In 2015, foresters noticed wide patches of pines turning brown as a result of an outbreak of Dothistroma needle blight, a disease that has spread through 11,000 acres of forest in Gustavus since 2009, claiming 60 percent of pines in some areas.

The fungus infects a tree’s needles, eventually killing the tree.

In Haines, the outbreak has affected fewer than 2,000 acres. “We saw some pine mortality and considerable crown dieback… Some affected trees had produced ‘stress cones,’ excessive numbers of cones as a last-ditch reproductive effort,” Mulvey said.

“There’s some mortality but it looks like the stands are going to do nicely, short of a permanent outbreak,” she said.

Three conditions are required to spread the fungus to epidemic levels: Temperatures between 63-70 degrees F., precipitation, and three consecutive days of those two factors in combination.

“To have a really severe outbreak that results in tree mortality, these outbreak conditions probably need to occur over multiple consecutive years,” Mulvey said.

Summer rains in Southeast Alaska are typically cool. But with an increase in temperatures of a few degrees and precipitation over a number of days, the disease pathogen increases exponentially, Mulvey said.

Canadian scientists believe the spread of the disease is a climate change issue.

“It’s definitely a weather issue,” Mulvey said. “If summers warm up and we get into those conditions, it’s something that we’d look for. It wouldn’t take a big change of weather to get into that window.”

Shore pines, sometimes mistaken for lodgepole pines, are the common pine of the Chilkat Valley. Stands of them can be found in muskegs and rocky slopes where other trees have difficulty taking root.

Mulvey said there’s considerable scientific information about the Dothistroma fungus, as it also afflicts radiata pines in New Zealand and lodgepole pines in British Columbia.