Sudden Oak Death (SOD), a serious exotic tree disease, threatens the survival of tanoak and several oak species in California. Currently, SOD infects trees in 14 coastal California counties, from Monterey to Humboldt. The disease, which was estimated to have killed over 50 million oaks and tanoaks over two decades, has changed the coastal forests composition in Northern California and Southern Oregon.
Though SOD occurs in patches, the overall infection area continues to grow with each passing year. Researchers had previously discovered that Phytophthora ramorum, the pathogen that causes SOD, most often spreads on the leaves of infected California bay laurel and tanoak. Forest managers can use proactive methods for...
- Author: Kara Minke, kjmanke@berkeley.edu, (510) 643-7411
In 2014, plant biologists with the California Department of Agriculture reported an alarming discovery: native wildflowers and herbs, grown in nurseries and then planted in ecological restoration sites around California, were infected with Phytophthora tentaculata, a deadly exotic plant pathogen that causes root and stem rot.
While ecologists have long been wary of exotic plant pathogens borne on imported ornamental plants, this was the first time in California that these microorganisms had been found in native plants used in restoration efforts. Their presence in restoration sites raised the frightening possibility that ecological restoration, rather than returning disturbed sites to their natural beauty, may...
- Author: Katie Harrell
Overall, 3.5 percent of the trees (based on those areas sampled during the blitzes) were found to be P. ramorum positive, a threefold drop from 2017. Yet, in San Mateo, Santa Clara and...
Drought is decreasing but not defeating the pathogen that causes sudden oak death, according to a citizen science-assisted survey conducted this spring by a UC Agriculture and Natural Resources forest pathologist.
Results of the 2015 Sudden Oak Death Blitz survey reveal coastal mountain infestations in areas such as Big Sur (19% infection), the Santa Cruz Mountains (13% infection), and western Sonoma County (12% infection) remain high despite an overall decline in infection rates from 4.4% to 3.7% across California's 15 infested counties.
Sudden oak death (SOD) symptoms have been seen in Alameda, Contra Costa, Humboldt, Lake, Marin, Mendocino, Monterey, Napa, San Francisco, San Mateo, Santa Clara, Santa Cruz, Solano,...
- Author: Pamela Kan-Rice
Sudden oak death is a misnomer because it doesn't fell a tree like a lightning strike nor does the disease limit itself to oaks. Nonetheless, the moniker has stuck and UC scientists remain committed to containing the culprit.
UC, federal and state agencies and landowners in Humboldt County recently received national recognition for their collaborative efforts to halt the spread of sudden oak death. Kathleen Merrigan, U.S. Department of Agriculture deputy secretary, praised the partnership during her visit to Davis on May 16.
Yana Valachovic, UC Cooperative Extension advisor in Humboldt County, and
