Summer survival of Phytophthora ramorum in California bay laurel leaves

Abstract

Sudden oak death manifests as non-lethal foliar lesions on bay laurel (Umbellularia californica), which support sporulation and survival of Phytophthora ramorum in forest ecosystems. Infected bay laurel leaves are more likely to abscise than uninfected leaves, resulting in an accumulation of inoculum at the forest floor. The pathogen survives the dry summers in a proportion of attached bay leaves, but the histology of colonization during the survival phase and the propagules responsible for survival are unknown. This study focuses on summer pathogen survival associated with bay laurel in redwood-tanoak and mixed evergreen forests with specific objectives including: i) detection of P. ramorum in leaf litter and soils throughout summer, ii) quantification of chlamydospores on and within attached symptomatic leaves, and in fresh and aged litter, iii) determination f chlamydospore germination, and, iv) assessment of pathogen survival within litter and canopy leaves, addressing the location of viable inoculum within foliar tissues.

Parent Publication

• Proceedings of the sudden oak death third science symposium

Citation

Fichtner,Elizabeth J.; Rizzo, David M.; Lynch, Shannon C.; Davidson, Jennifer ; Buckles, Gerri; Parker, Jennifer. 2008. Summer survival of Phytophthora ramorum in California bay laurel leaves. In: Frankel, Susan J.; Kliejunas, John T.; Palmieri, Katharine M., tech. coords. 2008. Proceedings of the sudden oak death third science symposium. Gen. Tech. Rep. PSW-GTR-214. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station. pp. 357-358