Document: PAT-3-55-6
Incidence and spread of white pine blister rust: Implications for disease dynamics.
MALONEY, P.E.* and D.M.RIZZO
University of California, Davis, CA 95616 1
Abstract:
White pine blister rust (WPBR), caused by Cronartium ribicola, is an exotic pathogen that infects and kills 5-needle pine species in the western United States. In addition to pine, C. ribicola must also infect Ribes spp. to complete its life-cycle. Tree species in the Sierra Nevada that are affected by this disease include sugar pine (Pinus lambertiana), western white pine (Pinus monticola) and whitebark pine (Pinus albicaulis). Sugar pine grows in mixed-conifer forests in the lower montane zone, western white pine grows in upper montane and subalpine zones, and whitebark pine exists only in the subalpine zone. To understand patterns of pathogen spread and the effect this disease may have on host population dynamics we surveyed 5-needle pine species in 30-40 ha grids in mixed-conifer forests in the central Sierra Nevada and in a subalpine location in the Lake Tahoe Basin, in the northern Sierra Nevada. In addition, we ran transects in 17 different upper montane/subalpine locations around Lake Tahoe. In mixed-conifer forests, WPBR incidence is largely dependent on topographic features, that favor environmental conditons suitable for rust infection, as well as the presence of Ribes. In the more environmentally homogenous subalpine location, WPBR incidence was less variable and more uniformly spread. However, across the Lake Tahoe Basin WPBR incidence is quite variable. Much of the variablity associated with incidence across the Lake Tahoe Basin is due to differences in environmental conditions, and possibly genetic heterogeneity and isolation of hosts. Where environmental conditions are favorable for WPBR, we have observed increased mortality among smaller pine recruits.
Keywords: White pine blister rust, host-pathogen interactions
This abstract is being presented at: 4:30 PM in session:
Oral Session #15: Parasitoids and Diseases.