Sudden Oak Death continues to spread

By Jane Stebbins, Pilot staff writer July 20, 2012 10:41 pm

Sudden Oak Death disease has spread again, this time to a campground 15 miles southeast of Brookings – and a now-defunct nursery between Gold Beach and Brookings.

The Rogue River-Siskiyou National Forest announced that the diseased trees were located in the Wheeler Creek drainage near Chimney Camp Trail  No. 1279. They were spotted in April during regularly scheduled aerial surveys conducted by the Oregon Department of Forestry and the U.S. Forest Service. The trail has now been closed to the public after scientists verified it is the mold that causes SOD.

Of even greater concern, particularly to state Department of Agriculture (DOA) officials, is the rhododendron, mountain laurel (kalmia) and pieris plants people purchased from Rebecca’s Greenhouse earlier this year. People who purchased infested plants there could easily have brought the fungus back to areas not affected by the disease.

 

No infected plants were found at the nursery during DOA’s routine inspection last year; however, 13 infected plants were found this year.

Specific species affected include Kalmia latifolia, Pieris japonica, and Rhododendron varieties Bessie Howell, Betty Bob, Black Sport, Maximum Roseum and Seta plants.

Gardeners are asked to examine those plants for visible symptoms and, if seen, contact Nancy Osterbauer at the state DOA at 503-986-4666 or the Brookings office of the Oregon Department of Forestry at 541-469-5040.

The nursery cooperated with the DOA to eradicate the disease from its premises. Recent inspections there have found no additional infected plants, yet officials will continue to monitor the site to ensure the eradication was successful.

The nursery is located in a quarantine area that has infected plants and trees in the natural environment. But testing has shown that the disease confirmed at the nursery is not the same strain as the fungus in other areas in the county and therefore, was likely brought into the nursery from outside the area.

Forestry officials are also busy working to eradicate the infestation at Chimney Camp.

“We are immediately taking action to inhibit the spread of this disease,” said  Alan Vandiver, district ranger on the Gold Beach Ranger District. He added that a local contractor will begin treating the infested trees and protect surrounding vegetation.

Sudden Oak Death (SOD) was discovered in the United States in 1995, and the mold that specifically attacks trees locally was identified in 2001.

 The disease is caused by the water mold, Phytophthora ramorum. The organism affects more than 100 species of trees, shrubs, herbs and ferns, and primarily attacks tanoak, Pacific rhododendron, evergreen huckleberry and occasionally Oregon myrtlewood.

The name “sudden oak death” refers to the ability of the pathogen to infect oaks and tanoak through the tree bark, causing a canker that rapidly kills the tree. Black or red ooze bleeds from the cankers, staining the bark and killing mosses that grow on it. Once crown dieback begins, leaves often turn from green to pale yellow to brown within a few weeks. Yet the tree can live for up to 10 more years, all the while providing a safe haven from which the spores can spread.

The last reported outbreak occurred last fall in Cape Sebastian State Park and six miles north of the 162-square-mile quarantine area established in the county. That outbreak is more than 12 miles from the nearest known infected tree, the longest distance scientists had seen the mold travel in the 10 years they have been monitoring it.

Usually, if the pathogen has traveled that far, it hasn’t done so by rain or wind as it normally does, but rather by people who unknowingly bring it in on their shoes or car tires, or by taking infected material – moss, wood and bark – out of an infested area.

It has killed millions of oaks and tanoaks in California, and about 1,500 tanoaks on 350 acres in Oregon.

SOD is well adapted to the mild, wet conditions of Curry County where it has affected less than 40 square miles.

The mold produces small spores that easily break off infected leaves and twigs and can be spread in rain splash and wind. People can accidentally spread SOD long distances by moving infested soil, wood, leaves or stems that become attached to their boots and clothes while hiking through an infested area.

Various agencies are working on public and private lands in Curry County to stop the spread of SOD using a strategy of early detection and aggressive treatment. Such treatments include eradication, quarantines and public education.

Although it has only been found in California and Oregon, its presence concerns forestry officials in other parts of the United States because at least two eastern oak species – northern pin and northern red oaks – are highly susceptible to the disease, Vandiver said.

For more information about the area closure, call the Gold Beach Ranger District at 541-247-3600.

Photos of disease symptoms caused by P. ramorum can be found at http://www.suddenoakdeath.org/library/photos/plant-symptom-photos/.