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Ponderosa pines show signs of foliar disease

Matthew Weaver

Capital Press

Ponderosa pines in Eastern Washington are showing signs of foliar diseases. Washington State University Regional Extension Specialist Steve McConnell says small forest owners don't need to remove affected trees.

Ponderosa pines in Eastern Washington are showing signs of a disease that causes the needles to turn reddish brown, a Washington State University Extension regional specialist says, but the trees will likely recover.

Microorganisms that infect tree needles are the most evident problem, said Steve McConnell, based at WSU Extension’s Spokane County office. The main symptom is reddish-brown needles, typically on the lower branches and interior of the tree, where moisture creates the right conditions for the foliar pathogen.

McConnell said the disease is due to previous wet springs and became more noticeable this year, he said.

“We’re hoping this spring was not the same and the needles coming on this year will not be affected,” he said.

The disease may cause trees to grow a little less because it reduces the photosynthesis that occurs. But it isn’t usually severe enough to kill the tree.

The trees are likely to recover with a normal spring, McConnell said.

Ponderosa pine forests are prevalent in the Spokane area. McConnell has received several calls each day, and said the Department of Natural Resources is also receiving concerned calls. 

He recommends careful examination of needles on the ground for microbes.

“If that’s what’s affecting your trees, there’s probably nothing you need to worry about and nothing you need to do, just wait,” he said.

The problem is always present in low levels, McConnell said, usually by streams or ponds, in areas with the right moisture conditions, but it’s not usually so widespread.

“Usually these kinds of things are minor — when you’re in forestry, you go out and find it and you say, ‘That’s kind of cool, because I know that’s out there and I hardly ever see it,’” McConnell said. “This year, it’s everywhere.”

Some concerned forest owners have talked about cutting down afflicted trees, which isn’t necessary, he said.

“There’s actually been a few cases where people who are interested in harvesting have approached people and told them their trees were going to die and cut them out,” he said. “We don’t want people to be bluffed into making a timber harvest decision they don’t need to make.”

Online

http://forestry.wsu.edu/staff/

http://www.spokane-county.wsu.edu/Forest%20&%20Wildlife%20Resources/Ponderosa_Pine_Needle_Cast.pdf



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