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Abstract
The
Phytophthora ramorum eradication program in effect in Oregon has allowed for the rapid detection of new infection foci, typically before they develop within each stand and expand into adjacent sites. Yet despite gallant efforts, new locations that previously harbored no apparent infection have been identified each year since the original detection in 2001. Multiple factors may influence why and where each new infection occurs including, but not limited to, stand characteristics such as dominant understory and upper canopy vegetation, age and stem density (which influence microclimate variations within the stand), the distribution of host and non-host species, and the various possible dispersal mechanisms of the pathogen (Shaw 2004). Previous studies in California have found that landscape patterns of disease severity are poorly explained by variation at small scales (Condeso and Meentemeyer 2007); however detailed work on infestations at their origin, prior to local intensification, has not yet been performed. This study examined the stand and canopy characteristics and the local distribution of
P.ramorum around the first trees detected, if not the first trees infected, in a remote location. We further set out to document and characterize a site with infestation that has developed to an extent previously unseen in Oregon.
Parent Publication
Citation
Peterson, E.; Botts, M.; Hansen, E. 2009. Stand structure and local distribution of
Phytophthora ramorum in Oregon forests. In: Goheen, E.M.; Frankel, S.J., tech. coords. Proceedings of the fourth meeting of the International Union of Forest Research Organizations (IUFRO) Working Party S07.02.09: Phytophthoras in forests and natural ecosystems. Gen. Tech. Rep. PSW-GTR-221. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 306-309.
