Incidence of White Pine Blister Rust in Maine After 70 Years of a Ribes Eradication Program. W. D. Ostrofsky, Cooperative Forestry Research Unit, College of Forest Resources, University of Maine, Orono 04469. T. Rumpf, D. Struble, and R. Bradbury. Maine Forest Service, Augusta 04333. Plant Dis. 72:967-970. Accepted for publication 26 June 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0967.

Effectiveness of a Ribes eradication program for control of white pine blister rust was evaluated by comparing the incidence of the disease in areas never treated for Ribes with areas from which Ribes were regularly eradicated over the past 70 years. White pine stands were sampled to determine the effect of treatment (whether or not Ribes were controlled), tree size class, and hazard rating on disease incidence. Disease incidence, as measured by the number of infected trees, is lower (3.8%) in areas treated for Ribes compared with areas with no treatment (9.1%). Rust incidence is lowest in reproduction stands, and highest in pole stands. Hazard zone ratings did not reflect disease levels. Survey results indicate that a significant reduction in the incidence of white pine blister rust on a statewide level has been achieved through the Ribes control effort.

Keyword(s): Cronartium ribicola, disease survey, eastern white pine.