Newly found disease could threaten Southeast Alaska spruce

A fungus that’s damaged trees in Southcentral and Interior Alaska has been discovered for the first time in Southeast.

But there’s a chance its spread could be stopped.

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Forest Pathologist Robin Mulvey walks down the causeway to the Shrine of St. Therese, a forested island about 20 miles northwest of downtown Juneau.

“Right here you can see a small tree. It’s about 4 inches in diameter and it’s just a stump now because we removed that tree,” Mulvey said. “This was a fairly heavily infected tree, at least in the lower branches.”

The infection was spruce bud blight, which damages or kills the growing tips of branches. It was discovered here in late June, the first reported sighting in the region.

The blight could be a problem, because it infects Sitka spruce, one of the most common trees in Southeast Alaska’s rainforest.

“Right now, I’m considering it potentially a significant threat,” Mulvey said. “I’ll be incredibly happy to be wrong about that.”

Mulvey, who works for the U.S. Forest Service, explains that Southeast’s Tongass National Forest has just what the blight likes.

“The ideal weather conditions for the pathogen are temperatures between 55 and 65 degrees Fahrenheit, with precipitation,” Mulvey said. “If you’ve been in Juneau this summer, you know we’ve had very conducive weather conditions for this pathogen.”

The fungus is not easy to spot. It’s black and looks like a dead, crusty coating on the buds.

It’s actually a group of small, spherical fruiting structures.

If it doesn’t kill a bud, it hampers its growth, leaving another sign, a small, twisted branch with few needles.

“This is going to spread through spores moving on the air and it’s also going to spread through spores moving through rain splash,” Mulvey said.

But no one’s sure how the spruce bud blight found its way to this one, small patch of Southeast forest.

Mulvey said it’s unlikely it came in on the clothes or boots of one of the shrine’s many visitors.

It’s often found on Colorado blue spruce, a common ornamental plant used in landscaping. But her team found no infected trees in the area or at a nearby arboretum.

Mulvey said they were looking for another pathogen, the spruce aphid, when they came across the infestation.

“We just happened to turn and look at this spruce tree. And I said, ‘Hey! The shoots on that spruce look a little bit bent.’ So we went in for a closer look,” Mulvey said.

Spruce bud blight was first found in Homer four years ago, though it took until last year to figure out what it was. It’s also been identified elsewhere on the Kenai Peninsula and in Anchorage and Fairbanks.

Forest Service Plant Pathologist Lori Winton, who is based in Fairbanks, said her first encounter also was a surprise.

“The first time I saw it, I was skiing in the forest near Anchorage and I pretty much fell face-first right into a tree that had it,” Winton said.

That was about two years ago, and it wasn’t clear what it was.

Then, an article in a scientific journal described outbreaks on blue spruce plantations in central Europe’s Czech Republic.

“Suddenly, there were DNA sequences available that matched,” Winton said. “I had an identification and frankly it was a rather alarming identification.”

The potential for extensive damage in Southeast’s forests, or those statewide, is not known. And since no one’s sure how it got to Alaska, it’s not clear how rapidly it could spread.

Winton said there’s also a chance spruce bud blight could have been here all along and just hadn’t been spotted. After all, it is a big state.

“That’s currently the question, is whether it’s native to North America or not — or Alaska,” Winton said.

Winton said it could take a year of lab work to figure that out.

The blight has been found in eastern Canada, but not throughout the United States.

Mulvey wonders about the same question back in Juneau.

“Part of me says, ‘What are the chances that we detected the only site of infection in Juneau?’” Mulvey said. “I think the chances are pretty small.”

But if it isn’t here naturally, there’s a chance it could be stopped.

“I just have to do what I can to try and prevent any further spread, while it still seems feasible,” Mulvey said.

Mulvey’s team is continuing its search for spruce bud blight in Southeast. It’s also asking for public help. She suggests checking landscape plants on your own property, because it seems most common in developed areas.

“Look really closely at any dead buds on your spruce trees and if you see these small, spherical black fruiting structures, please give us a call because we’d love to come out and take a look,” Mulvey said.

And that’s just what was she doing during our visit to the Juneau landmark.

Mulvey and shrine volunteer Brian Flory were using binoculars to check out higher branches near the infected trees that were removed or trimmed. And sure enough, they found more.