OSU warns of sudden oak death threat along coast

Oregon State University Extension Office

Sudden oak death (SOD), caused by a non-native pathogen Phytophthora ramorum, has killed more than 1 million oak and tanoak trees in 15 coastal counties in California and thousands of tanoaks in Curry County, Oregon. The pathogen also causes foliar blights on many native shrub species including Pacific rhododendron and evergreen huckleberry. As SOD spreads into new areas in coastal Oregon the effects extend to small and large landowners, restoration practitioners and urban areas. Local Extension and natural resource agency offices frequently answer questions related to disease identification, treatment options, quarantine rules and management approaches.

Many landowners were uncertain of what species to plant within SOD-infested areas, requesting a list of native planting options. There are also landowners that remain unaware that the disease may spread to their property. In 2018, a Sudden Oak Death education and outreach program was developed to spread awareness in communities impacted by the disease. The program delivers a general background on disease spread, prevention and treatment while training participants in disease recognition and reporting. Research science presentations give a more thorough examination of specific topics and are also an opportunity for participants to learn how university research programs address local issues. In addition, neighborhood workshops held in local community halls have been a successful format to reach residents in rural 191 areas.

In the spring of 2021, a different clonal lineage of Phytophthora ramorum was discovered in Port Orford in Curry County. This clonal lineage had never before been found in the wildlands of North America. Several species have recently been discovered in restoration nurseries and wildland plantings in California. Best management practices can be taken by small restoration nurseries to help reduce the risk of infestation.

In response, faculty in the Oregon State University Extension Service Forestry and Natural Resources Program wanted to make sure that information about this risk and key prevention strategies were available to small restoration nurseries and practitioners. In a collaborative effort, Extension faculty at OSU and Washington State University developed a publication, Preventing Phytophthora Infestations in Restoration Nurseries, a key to protecting wildland plant communities.

Part of the group’s outreach included a live webinar hosted by the Bonneville Environmental Foundation with support from the Climate Resilience Fund. The audience included experts, learners, restoration groups and practitioners – all trying to strengthen networks and address risk prevention strategies across a wide geographic area. One attendee, a Port Orford community member, created an infographic that could be printed and also shared on social media.

OSU Extension has published two other guides for preventing the spread of sudden oak death. “Sudden Oak Death: Prevention, Recognition, Restoration,” is targeted to homeowners, small woodland owners, resource managers and conservation groups. The other is “Sudden Oak Death and Phytophthora ramorum: A Guide for Forest Managers, Christmas Tree Growers, and Forest Tree Nursery Operators in Oregon and Washington.”

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