Scientists have recently discovered a deadly plant disease that’s infecting fir trees in the Pacific Northwest.
This “European” strain of sudden oak death (Phytophthora ramorum) appeared in southwest Oregon a few years back, and it was known to spread to fir trees in Europe. This disease has killed millions of tanoak trees and several oak tree species (coast live oak, California black oak, Shreve oak and canyon live oak).
Differing from the European strain of sudden oak death, the North American strain has been killing tanoak throughout Curry County for years.
The European strain has forest managers worried because of the potential to infect the commercial timber base.
“This report shows that it is able to infect Douglas fir and grand fir. And it’s doing it in the forest,” Oregon State University forest pathologist Jared LeBoldus, lead author of the study, told OPB.
Sudden oak death appeared in Douglas and grand fir saplings growing under an infected tanoak tree, and the reports say that they have wilted tips, needle loss and discoloration.
According to the California Oak Mortality Task Force, all of the natural areas found with infection are cool, moist and frequently foggy. Along with natural infection in woodland and forested areas, Phytophthora ramorum has also been found in the nursery system on host and associated plants.
“The main concern would be that the infections are on the new growing points,” LeBoldus told OPB. “So, if all those parts are killed, the tree isn’t necessarily be able to grow in its normal way it would if it’s not infected.”
LeBoldus stressed that scientists have yet to see a fir tree die from this disease, but it is believed to take a couple of years for a tree to die from sudden oak death.
First appearing in a Curry County, Oregon, nursery in 2012, the European strain of sudden oak death spread from an infected rhododendron to tanoak in the surrounding forest.
Funding for eradication of the strain has been a focus of state and federal agencies, and it is believed to still be relatively geographically contained near the Pistol River.
Fire is being used to destroy host material in the forest.
“We believe that it is more aggressive,” Ellen Michaels Goheen, a pathologist for the U.S. Forest Service, told OPB. “It appears to be behaving that way, even though we have not seen major impacts to conifer species. It’s worth being cautious and try to treat those as thoroughly as we can.”