Skip to Main Content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Home > Search > Publication Information

  1. Share via EmailShare on FacebookShare on LinkedInShare on Twitter
    Dislike this pubLike this pub
    Author(s): J. M. Davidson; H. A. Patterson; A. C. Wickland; E. J. Fichtner; D. M. Rizzo
    Date: 2011
    Source: Phytopathology 101: 492-501
    Publication Series: Scientific Journal (JRNL)
    PDF: View PDF  (376.94 KB)


    The transmission ecology of Phytophthora ramorum from bay laurel (Umbellularia californica) leaves was compared between mixed-evergreen and redwood forest types throughout winter and summer disease cycles in central, coastal California. In a preliminary multisite study, we found that abscission rates of infected leaves were higher at mixed evergreen sites. In addition, final infection counts were slightly higher at mixed-evergreen sites or not significantly different than at redwood sites, in part due to competition from other foliar pathogens at redwood sites. In a subsequent, detailed study of paired sites where P. ramorum was the main foliar pathogen, summer survival of P. ramorum in bay laurel leaves was lower in mixed-evergreen forest due to lower recovery from infected attached leaves and higher abscission rates of infected leaves. Onset of inoculum production and new infections of bay laurel leaves occurred later in mixed-evergreen forest. Mean inoculum levels in rainwater and final infection counts on leaves were higher in redwood forest. Based on these two studies, lower summer survival of reservoir inoculum in bay laurel leaves in mixed-evergreen forest may result in delayed onset of both inoculum production and new infections, leading to slower disease progress in the early rainy season compared with redwood forest. Although final infection counts also will depend on other foliar pathogens and disease history, in sites where P. ramorum is the main foliar pathogen, these transmission patterns suggest higher rates of disease spread in redwood forests during rainy seasons of short or average length.

    Publication Notes

    • You may send email to to request a hard copy of this publication.
    • (Please specify exactly which publication you are requesting and your mailing address.)
    • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Davidson, J. M.; Patterson, H. A.; Wickland, A. C.; Fichtner, E. J.; Rizzo, D. M. 2011. Forest type influences transmission of Phytophthora ramorum in California oak woodlands. Phytopathology 101: 492-501. DOI: 10.1094/PHYTO-03-10-0064


    Google Scholar


    geographic mosaic, host × pathogen interaction, Lithocarpus densiflorus, microclimate, Quercus agrifolia, sudden oak death

    Related Search

    XML: View XML
Show More
Show Fewer
Jump to Top of Page