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Posts Tagged: Sudden Oak Death

High interest in SOD spread to San Luis Obispo County

Central Coast residents, officials, ranchers and representatives of conservation organizations came out in force to a November UC Cooperative Extension meeting sounding an alarm about the recent detection of Sudden Oak Death (SOD) in San Luis Obispo County trees, reported Kathe Tanner in the San Luis Obispo Tribune.

This was the first such gathering in this county since tests confirmed that the disease made its way south of Monterey County, according to event coordinator Mary Bianchi, director of UC Cooperative Extension in SLO County. But there will be more meetings to come, she said.

California bay laurel infected with the pathogen that causes Sudden Oak Dealth.

Previously confirmed infestations of the disease stayed north of the Monterey County border with San Luis Obispo County. Because SOD spreads by wind and rain, experts believe the prolonged California drought inhibited the spread further south. However, recent tests confirmed the SOD pathogen, phytophthora ramorum, on oaks along the parking lot at Salmon Creek, and in bay laurel trees along Santa Rosa Creek Road, west of Atascadero near Highway 41 and along Stenner Creek and Prefumo Canyon in San Luis Obispo.

Another intensive survey to be conducted by foresters and volunteer citizen scientists in the spring will include Cambria neighborhoods, ranches and other areas. In the meantime, residents were asked to keep an eye out for SOD symptoms in local bay laurel and oak trees. SOD lesions show up as pixilated brown, black or gray areas on leaf tips. Oozing cankers on an oak tree, with sap coming out of the trunk but with no wound evident on the bark, is another sign that the trees could be infected with the pathogen that causes SOD.


The most reliable early symptom of sudden oak death is dark sap exuding from trunk base, as on this coast live oak. (Photo: UC IPM)
For more information from the University of California about Sudden Oak Dealth in California, visit

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Posted on Friday, November 18, 2016 at 10:17 AM

Sudden oak death still a threat and still spreading

Humboldt County tanoak trees that have succumbed to sudden oak death.
Thirteen years after sudden oak death was first detected in California, the disease's range in northern coastal areas of California and southwest Oregon continues to grow, according to a report by Michael Joyce on Jefferson Public Radio.

Joyce interviewed Yana Valachovic, a forest advisor for UC Agriculture and Natural Resources in Humboldt and Del Norte counties. Valachovic is also director of the UC ANR Cooperative Extension offices in Humboldt and Del Norte.

"For me, the challenge is communicating to the public the disease has not gone away; in fact, it's actually getting substantially worse," Valachovic said.

Sudden oak death is caused by the pathogen Phytophthora ramorum. Currently less than 2 percent of Humboldt County's 2.25 million acres of forest are impacted by sudden oak death. But the average annual rate of expansion per year is 3,500 acres, Valachovic said. One challenge related to containing the disease is the structure of California forest agencies.

"The wildlands of California don't have a single agency that's responsible for controlling invasive introductions," she said. "Secondarily, there is no funding source that is set aside to manage these kind of epidemics. And so everything is piecemealed together: piecemealed responsibility, piecemealed in funding to address these issues."

Furthermore, Forest Service funds can only be used for monitoring, containment and education. 

Joyce concluded the story with a question: "How will we learn more about this disease that is spreading through our forests at a clip of about 5 miles per year?"

Read more about sudden oak death on the California Oak Mortality Task Force website.

Posted on Friday, June 19, 2015 at 10:35 AM

Drought is slowing the spread of sudden oak death

A coast live oak killed by sudden oak death. (Photo: Bruce Hagen)
Finally, some good news about the drought. Dry conditions have apparently curbed the spread of sudden oak death in 12 coastal California counties, reported Guy Kovner in the Santa Rosa Press Democrat.

"If we had one more year of drought, it would really be ideal," said Matteo Garbelotto, UC Cooperative Extension specialist in the Department of Environmental Science, Policy and Management at UC Berkeley.

The article said Garbelotto isn't hoping for more drought, but evidence shows that the drought is helping reduce SOD infection rates and in some cases is curing infected trees, "because the pathogen dies."

Each spring, the UC Berkeley SOD lab hosts a "blitz" to gauge the spread of Sudden Oak Death. Volunteers fan out across areas susceptible to SOD and collect leaf samples for analysis.

In the Cloverdale area, where an outbreak was confirmed last year, none of the trees sampled had the disease this year, the article reported.

"I would say it is there, but we just didn't find it," Garbelotto said.

East of Highway 101, the rate dropped from 26 percent infected last year to 23.3 percent in 2014, the story said.

Complete SOD blitz results will be available Sept. 29 on the UC Berkeley Forest Pathology and Mycology Lab website.

Posted on Thursday, September 25, 2014 at 10:51 AM

Sudden oak death continues to spread in California

Cleaning boots after a hiking trip helps prevent the spread of sudden oak death.
Sudden oak death is creeping into Carmel Valley, and scientists have found infected trees in Gilroy and Prunedale, reported the Salinas Californian.

Warm weather seems to be keeping SOD out of the Salinas Valley, but it is having a deadly effect on the surrounding forests.

“The organism has a really significant impact on our forests,” said Matteo Garbelotto, UC Cooperative Extension specialist in the Department of Environmental Science, Policy and Management at UC Berkeley. He said that adult tanoaks – an evergreen species closely related to oaks – are almost entirely wiped out in some areas.

To help prevent the spread of sudden oak death, people visiting invested areas should not remove leaves or branches and should clean dirt from their shoes before leaving.

Posted on Monday, December 16, 2013 at 9:27 AM

Citizen scientists being mobilized in Sonoma County

A Sudden Oak Death "Blitz" planned for Sonoma County June 15-16 will prepare local residents to spot infected plants, collect samples from their neighborhoods and submit them for laboratory testing, reported the Kenwood Press.

The session is hosted by UC Cooperative Extension Master Gardeners and Matteo Garbelotto, UCCE specialist in the Department of Environmental Science, Policy and Management at UC Berkeley.

Trees susceptible to sudden oak death include California bay laurel, tan oak, live oak, black oak, canyon live oak and shreve oak. After the laboratory analysis is complete, Garbeletto will schedule a return visit to discuss the findings of the survey and provide guidelines for action.

"If the disease front is 100 yards away, then one needs to decide whether some of his oaks should be protected," Garbeletto said. "For oaks up to 30 inches in diameter, removal of small and medium size laurels for a 10-yard radius around the oak trunk plus the application of AgriFos on the bark each year or every other year will protect the oak."

The information collected by the citizen scientists will also be added to Garbelotto's OakMapper website, a portal where SOD appearance in California is monitored.

Posted on Wednesday, May 15, 2013 at 9:23 AM

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