Tracking sudden oak death 


People who want to participate in this weekend’s local blitz are asked to sign up online at and to start by attending an hour-long training session Saturday morning at four locations in Santa Rosa, Graton, Cloverdale and Sonoma (see the website for details).

Spring rains brought relief to a drought-weary region, filling North Coast reservoirs and farm ponds and turning grassy hills a glorious emerald green.

But the wet, sometimes windy weather was also ideal for Phytophthora ramorum, the insidious pathogen that causes sudden oak death, a disease that has killed more than 3 million trees in coastal forests from Monterey to Humboldt counties since 1995, when it was discovered in Marin County.

The pathogen can be spread by human footprints and nursery plants, but in nature it rides in water droplets blown from the leaves of bay laurel trees, a host species that abounds in close proximity to the oak and tanoak trees that sudden oak death kills.

California’s four-year drought slowed the disease’s spread considerably, but officials are wary of a widespread rebound, including Sonoma County, owing to a comparatively soggy spring. Santa Rosa has recorded 12.5 inches of rain since March 1, compared with 1.5 inches in the same period last year.

“We think we’ll see a bump this year,” said Lisa Bell, the county’s sudden oak death program coordinator. “We want to see what the pathogen does coming out of a drought.”

The means for that assessment is the SOD Blitz, an annual volunteer effort organized by the UC Berkeley Forest Pathology and Mycology Lab. More than 40 people have signed up for the Sonoma County blitz on Saturday and Sunday, and Bell said she’s hoping for many more volunteers who will be trained to collect samples — primarily bay leaves — that will be analyzed at the Berkeley lab.

Read more at: North Coast rains a boost for sudden oak death | The Press Democrat