The status of a project to eradicate sudden oak death on the southern Oregon coast is a mixed bag of results so far. While a five-year multi-agency effort to completely get rid of the tree-killing disease has not yet reached its ultimate goal, officials are encouraged that it hasn't spread far beyond its original detection site northeast of Brookings in Curry County. The site has included less than 88 acres of infected plant material, and remains the only place in Oregon where Phytophthora ramorum– the fungus that causes sudden oak death– has been found in the natural environment.

 

"If you look at the results since 2001 when we first found the disease, we have definitely been successful at slowing the spread," says Dan Hilburn, administrator of Oregon Department of Agriculture's Plant Division. "There is no question that had we not done what we have, sudden oak death would have spread throughout the county and would probably be in other Oregon counties by now."

 

The fungus-caused disease has already left a trail of dead trees in central and northern California ever since it was first detected in the San Francisco Bay Area in the mid-1990s. P. ramorum invades susceptible trees through the bark, killing the entire tree or portions of the tree. Certain species of oak commonly found in southwest Oregon, including tanoak and black oak, are very susceptible. But P. ramorum also infects rhododendron, huckleberry, madrone, myrtle, and several other shrubs.

 

Nowhere else in the world has there been success in eradicating P. ramorum in the wild from an area that has been infected. A diligent policy of cutting, stacking, and burning infected trees and shrubs within the nearly 22-mile quarantined area of Curry County shows signs of working. Even though new sites continue to be found, the numbers are dramatically less than the first couple of years and most infected trees remain within the quarantine boundaries.

 

"The experts on P. ramorum tell us it is still worth trying to eradicate the disease from this site," says Hilburn. "They are encouraged so far with the progress we've made, even though it has been slow. We haven't gotten rid of the disease, but we're still on track of someday perhaps being able to."

 

Interagency cooperation has been a key to the project. The U.S. Forest Service (USFS) and Oregon Department of Forestry (ODF) have been responsible for aerial observation and detection of dead or diseased trees. ODF and ODA has been active in monitoring the spread of the disease on the ground. ODF has had the lead in cutting and burning the infected plant material while ODA monitors the success of the treatment. Oregon State University has provided the laboratory confirmation of P. ramorum when survey samples are taken. No single agency can provide the necessary resources to undertake the eradication project, but combined, success if possible.

 

Ellen Goheen, USFS plant pathologist, was part of the aerial survey that first detected sudden oak death in Oregon in 2001. After seeing tens of thousands of acres of dead trees in California, now spreading over 14 coastal counties, she wanted to keep Oregon from a similar fate.

 

"We still have the pathogen here, but we have it contained– certainly more so than in California," says Goheen. "I still think we have a good chance of eradicating it from Curry County."

 

The U.S. Forest Service and ODF plan to take another survey from the air in July and September, not only of the Curry County site but all other forest locations in southern Oregon where the susceptible tanoak and black oak species exist. When a dead tree is located, helicopters follow up by pinpointing the GPS coordinates of the tree. A ground crew is then sent in to verify a cause of the tree's death. In most cases– and in all cases outside the Curry County site– the cause of death is not P. ramorum. But officials want to make sure the rest of Oregon's natural environment remains unblemished by the disease.

 

On-the-ground efforts to eradicate P. ramorum have included the cooperation of landowners in Curry County. The quarantine also keeps potentially-affected plant material from leaving the area. Signs are posted at all entrances informing people of the quarantine.

 

Questions remain of how the disease made it to southwest Oregon. Every expert seems to have their own theory, but the fact remains that the nearest site of sudden oak death in the natural environment in 2001 was less than 275 miles to the south, in California.

 

"Most of the places where the disease is occurring are not near roads or people," says Hilburn. "It is hard to imagine the introduction in Oregon was caused by humans, but how does it skip 275 miles?"

 

Research shows the disease can spread through rain splash. That's why it is important to cut down affected trees quickly to take them out of the canopy and keep the fungus from splashing onto other trees and shrubs. The disease can also be found in the soil and can survive in water. USFS and ODF have been baiting more than 70 streams in southwest Oregon with rhododendron leaves that later can show symptoms of infection. The intensive monitoring and survey work underscores the importance of keeping the disease in check and confined to the original Curry County site.

 

The cost of all the survey, monitoring, and eradication work in southwest Oregon the past five years is approaching a million dollars. But the cost of allowing sudden oak death to spread beyond its present borders in Oregon is hard to fathom. Not only is the state's forest ecosystem and timber industry at risk, an important nursery industry is doing all it can to keep the disease from establishing in some of the susceptible plants grown and shipped from Oregon. ODA efforts to inspect and certify all Oregon nurseries as free of P. ramorum continues at the same time eradication efforts are underway in Curry County.

 

Border security takes on a whole new meaning in Oregon when it comes to sudden oak death.

 

For more information, contact Dan Hilburn at (503) 986-4663.