White Pine Blister Rust on Limber Pine in South Dakota. J. E. Lundquist, USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO 80526. B. W. Geils, and D. W. Johnson. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO 80526; and USDA Forest Service, Lakewood, CO 80225. Plant Dis. 76:538. Accepted for publication 13 November 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0538A.
White pine blister rust, caused by Cronartium ribicola J. C. Fisch., here reported for the first time from South Dakota, was found on limber pine (Pinus flexilis E. James) and wax currant (Ribes cereum Douglas) in a 2.5-ha stand at Cathedral Spires in the Black Hills National Forest. The infested stand is the easternmost natural extension of limber pine and is isolated from the nearest limber pine stand by 160 km and the nearest known population of C. ribicola by 240 km. Diseased pines bore dying branches with fusiform swellings and ruptured bark associated with aecia. Aeciospores matched previous descriptions of C. ribicola when stained with lacto-phenol and cotton blue and viewed under a microscope. Aecia or uredina were found on about 10% of the host trees or shrubs, respec-tively. Voucher specimens have been deposited in the Forest Service Forest Pathology Herbarium, Fort Collins, Colorado (No. 6805-C).