Host Phenology and Leaf Effects on Susceptibility of California Bay Laurel to Phytophthora ramorum

TitleHost Phenology and Leaf Effects on Susceptibility of California Bay Laurel to Phytophthora ramorum
Publication TypeJournal Article
Year of Publication2016
AuthorsJohnston, SF, Cohen, MF, Torok, T, Meentemeyer, RK, Rank, NE
JournalPhytopathology
Volume106
Issue1
Pagination47 - 55
Date PublishedJan-01-2016
ISSN0031-949X
Abstract

Spread of the plant pathogen Phytophthora ramorum, causal agent of the forest disease sudden oak death, is driven by a few competent hosts that support spore production from foliar lesions. The relationship between traits of a principal foliar host, California bay laurel (Umbellularia californica), and susceptibility to P. ramorum infection were investigated with multiple P. ramorum isolates and leaves collected from multiple trees in leaf-droplet assays. We examined whether susceptibility varies with season, leaf age, or inoculum position. Bay laurel susceptibility was highest during spring and summer and lowest in winter. Older leaves (>1 year) were more susceptible than younger ones (8 to 11 months). Susceptibility was greater at leaf tips and edges than the middle of the leaf. Leaf surfaces wiped with 70% ethanol were more susceptible to P. ramorum infection than untreated leaf surfaces. Our results indicate that seasonal changes in susceptibility of U. californica significantly influence P. ramorum infection levels. Thus, in addition to environmental variables such as temperature and moisture, variability in host plant susceptibility contributes to disease establishment of P. ramorum.

URLhttp://apsjournals.apsnet.org/doi/10.1094/PHYTO-01-15-0016-R
DOI10.1094/PHYTO-01-15-0016-R
Short TitlePhytopathology