Sudden Oak Death

Effective immediately, the Animal and Plant Health Inspection Service (APHIS) is expanding the Phytophthora ramorum (P. ramorum) quarantine area in Del Norte County, California. APHIS is taking this action in response to the confirmation of P. ramorum in the county on September 19, 2020. The California Department of Food and Agriculture has established an intrastate quarantine for the areas in Del Norte County that mirrors the federal regulatory requirements as specified in 7 CFR 301.92.

P. ramorum is the pathogen that causes sudden oak death, ramorum leaf blight, or ramorum dieback. Sudden oak death was first reported in 1995 on tan oak in Mill Valley, Marin County, California. Through ongoing surveys, APHIS continues to define the extent of the pathogen's distribution in the United States and uses quarantine areas and public outreach to limit its artificial spread beyond infected areas. Details on APHIS-designated P. ramorum quarantine and regulated areas and the conditions to move regulated articles are in 7 CFR 301.92 and at the APHIS website.

Potatoes and oak trees don’t have a lot in common, but there is one thing, and it isn’t good – a fungal-like plant pathogen in the genus Phytophthora. One of the many invasive pathogens contained in this genus, P. infestans, was responsible for the Irish potato famine. Since the mid-1990s, though, Phytophthora has been attacking forest trees along the West Coast, with the pathogen P. ramorum, also known as "sudden oak death" (SOD). SOD was first detected in the San Francisco Bay Area; it has since spread throughout California. In 2001, SOD was discovered in southwest Oregon where it infected tanoaks trees. The discovery led to the formation of an interagency team that included researchers from the Agricultural Research Service (ARS) and Oregon State University (OSU), to develop strategies to mitigate the impacts of SOD.