Sudden Oak Death in Mattole watershed

The microbe that causes Sudden Oak Death has been detected in the Mattole watershed for the first time, according to results released last week from the plant pathology lab at the University of California at Davis.

The Mattole Restoration Council sampled eight streams throughout the Mattole for this microbe, Phytophthora ramorum, and it appeared in just one of those eight - Blue Slide Creek, just east of Ettersburg. The detection means that diseased trees are found somewhere in the Blue Slide watershed.

"We’re disappointed, but we are not that surprised to find Sudden Oak Death in Blue Slide Creek, since the disease has been well established just on the other side of the ridge in the Miller Creek drainage," said UC Cooperative Extension forest advisor Yana Valachovic.

Sudden Oak Death (SOD) was first observed in California in the mid-1990s. It causes high mortality in tanoaks, and is also hosted by many other forest species that are not significantly harmed by it, such as bay laurel and rhododendron.

"Although Sudden Oak Death has appeared in the Mattole, we believe there is still a good chance to slow its spread through the watershed," said Seth Zuckerman, director of the Mattole Restoration Council’s Wild & Working Lands Program. "By treating small islands of infestation, we hope to avoid having extensive tracts of standing dead tanoaks, with the fire hazard and erosion risk that they would cause."

The Mattole Restoration Council is asking landowners and residents to contact us if they notice tanoaks with cankers or bay trees with leaf lesions, so that we can get an idea of how far the disease has spread. (Photos of those symptoms can be found at and Council staff are available to take samples or advise landowners how to collect them, and send them for testing through UC Extension. "We remain ready to assist the MRC and landowners in searching out the disease and slowing its spread," Valachovic said.

To avoid inadvertently spreading the disease, the Council is asking that people avoid transporting bay laurel foliage out of the Blue Slide Creek drainage, including incidental leaves in loads of firewood. Tanoak firewood can also spread the infection if it gets wet, so any tanoak from that area should be kept dry.

The Mattole Restoration Council has been monitoring for SOD since 2007, with support from the U.S. Forest Service, the federal Bureau of Land Management, the Americorps Watershed Stewards Program, and the Bella Vista Foundation.

The Mattole Restoration Council works to conserve and restore the Mattole River Watershed. Since the Council’s founding in 1983, volunteers, staff, and local landowners have helped promote the conservation of native salmon and steelhead, the restoration of forestlands, and the improvement of the watershed’s biotic and human communities.

For more information, contact Seth Zuckerman or Andrew Nash at the Mattole Restoration Council: 707-629-3514.