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Diplodia Tip Blight of Ponderosa Pine in the Black Hills of South Dakota. D. W. Johnson, Supervisory Plant Pathologist, USDA Forest Service, Lakewood, CO 80225. Glenn W. Peterson, Plant Pathologist, USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Forestry Sciences Laboratory, University of Nebraska, Lincoln 68583; and R. D. Dorset, Forest Pest Specialist, Division of Forestry, South Dakota Department of Agriculture, Pierre 57501. Plant Dis. 69:136-137. Accepted for publication 25 July 1984. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1985. DOI: 10.1094/PD-69-136.

Diplodia tip blight was found for the first time on native ponderosa pine at scattered locations in the Black Hills of South Dakota. Infection of new shoots occurred annually in 19791982; however, extensive infection of second-year needle and branch tissues occurred only in 1979 after an unusually cold winter. Black Hills isolates of Diplodia pinea did not differ significantly from isolates from other areas in spore dimensions, spore septations, spore germination, germ tube growth, or growth in culture.