Lake County >> Since the discovery of a deadly tree disease in the south end of the county more than a decade ago, the area’s has been in quarantine.
It’s called Sudden Oak Death (SOD), but it’s not so sudden, and by the time the signs are visible — dead leaves, bleeding and brown cankers on trunks — it’s too late.
“Once you see the symptoms in the leaves, it appears to be happening quickly,” Katie Harrell, University of California, Berkeley public information officer, said. But in reality, it takes at least six months to several years from the time the tree is infected for it to die. Lake County’s confirmed case came in May 2004, making it the 13th California county added to the quarantine area.
Harrell is a member of the California Oak Mortality Task Force, a nonprofit group formed in 2000 responsible for coordinating a coalition of state, local and volunteer agencies in order to manage and minimize the spread of SOD. Although patches of dead trees are evident throughout Lake County, experts doubt the SOD is the cause.
The disease occurs when the trees are exposed to Phytophthora ramorum, which is also the culprit of Ramorum blight killing off leaves and twigs of more than 100 different trees, shrubs and plants.
“Really what it does is it’s a water loving organism,” Harrell said. “It gets into foliage at the spore level … and inhibits the tree’s ability to transport food and water.”
The relatively new pathogen was first discovered in 1995 when large numbers of tanoak trees were dying in Marin and Santa Cruz counties, according to task force research. The infestation has spread to 15 northern coastal counties in California, where it thrives in the cool, moist setting.
“Conditions are thought to spread the pathogen by dispersing spores from the leaves of foliar hosts,” according to the task force website, “Through wind-driven rain, water, plant material or human activity.”
An estimated one million trees have died from SOD in California alone, and it’s also shown up in Oregon and Washington, as well as some parts of Europe, according Oregon State University researchers.
The biggest impact it’s had locally, however, is only the added work for the Lake County Department of Agriculture, commissioner Steven Hajik said.
“It’s in one little small area within a half mile of the Sonoma County border,” Hajik said. “And we are talking about a little mild, square area.”
Patches of dead trees in Lake County can appear to be SOD or blight, but the cause is more likely due to the dry conditions of the drought, although he can’t say with certainty.
Hajik said he’s never actually seen a case in Lake County, likely due to the fact that it doesn’t mimic the coastal conditions in which the pathogen usually develops. Nonetheless, for the past decade, staff has had to inspect nurseries monthly with plants susceptible to the pathogen in order to comply with federal quarantine regulations.
They’ve yet to confirm another case.
Still, the quarantine dictates that plants which can potentially carry the disease such as Live Oak must stay within the county, Hajik said.
One example is the Mendocino National Forest, where a stipulation of its wood cutting permits in Lake County and Mendocino County, which also has SOD confirmed, is that firewood cannot be transported outside of quarantined areas.
SOD may not presently be an issue for the Lake County, and Harrell says there are preventative measures people can take to keep it that way.
The disease can be spread through moist organic material.
“During the wet time of the year, you can find [the pathogen] almost 100 percent of time on hiker’s shoes,” Harrell said. “Make sure you remove anything from shoes, even car tires. Rinse off so you don’t take it with you.”
She suggests staying on a paved path or going during the dry season whenever possible.
Homeowners should reserve pruning damaged trees during the dry time of the year, July through September, when the disease is less likely to spread.
Although, “it’s always present, we need to stay diligant and not become too relaxed during drier times,” Harrell said.
For more information, visit suddenoakdeath.org.
