Marin County was ground zero for sudden oak death, so it's only fitting that Marin is leading the way in eradicating the pathogen that causes the disease that has devastated oak forests in California and Oregon.
"The devastation in Marin turns out to be the place where we find solutions to meet this challenge," said Marin County Agricultural Commissioner Stacy Carlsen. "It's come full circle."
Although the origin of the disease is unclear, it is believed that the sudden oak death pathogen -- Phytophthora ramorum -- can spread from nursery plants into the wild, and more than 100 plants have been identified as hosts.
Since sudden oak death was discovered near China Camp State Park in the mid-1990s, it has spread to other counties, spurring emergency regulations to control the outbreak within commercial nurseries. A nursery found to have an infected plant is quarantined until it can be shown that the disease is no longer in the soil.
On Tuesday, scientists at the three-year-old National Ornamental Research Site at Dominican University in San Rafael unveiled breakthrough "green" technology they have developed using an ordinary commercial steamer to heat soil to 122 degrees, killing the sudden oak death pathogen.
"It's low-tech and high impact," said principal investigator Sibdas Ghosh, chairman of Dominican's Department of Natural Sciences and Mathematics.
Hosting a tour of the facility for regulators from the state Department of Food and Agriculture and the U.S. Department of Agriculture as well as some county agricultural officials, the researchers demonstrated how they pump steam into a soil bed covered with a tarp that lifts into a dome as the temperature rises inside and the soil gets to a temperature high enough to be fatal to the pathogen.
The low-cost steaming technique, which one county official called "back to the future," was first tried a year ago.
Since then, it has not only worked under controlled conditions at the half-acre campus research site, but also at a quarantined nursery in the San Joaquin Valley.
"It's a transformation of technology from the lab to the field," principal investigator Ghosh said.
Based on those successes, the USDA has asked the researchers to use their steaming technique at other quarantined nurseries in the state.
"It's critical for the nursery industry to have an operation like this," said Karen Suslow, a representative for California nurseries, pointing out that this is a cost-effective, efficient way of cleansing quarantined nurseries without using chemicals. "In the end, we're doing all this so we can safeguard the native environment, the forests."
The Dominican research site, the first outdoor facility devoted to studying the spread of the sudden oak death pathogen on nursery plants, was established in 2009 with funding from the U.S. Farm Bill.
"Having this kind of research and treatments available not only tells us how many plants are at risk and how they are at risk, but how we can treat the sites to eradicate the pathogen," said Fred Crowder, San Mateo County agricultural commissioner. "It's wonderful the federal government is recognizing the importance of this."
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