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Incidence of Pitch Canker Among Clones of Loblolly Pine in Seed Orchards. W. D. Kelley, Associate Professor, Department of Botany, Plant Pathology, and Microbiology, Auburn University, Auburn 36849. J. C. Williams, Associate Professor, Research Data Analysis, Alabama Agricultural Experiment Station, Auburn University, Auburn 36849. Plant Dis. 66:1171-1173. Accepted for publication 23 April 1982. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-1171.

Significant differences in severity of pitch canker (caused by Fusarium moniliforme var. subglutinans) were observed among loblolly pine (Pinus taeda) clones in American Can Company seed orchards at Myrtlewood and Bellamy, AL, in 1980. Disease severity was greatly diminished in the Myrtlewood orchard in 1981, although the relative ranking of clones for disease severity was similar to that of 1980. No differences in pathogenicity were found among nine isolates of the pathogen obtained from various clones and tested on loblolly seedlings in the greenhouse. Occurrence of the disease as early as 1978 in a shortleaf orchard adjacent to the loblolly orchard at Myrtlewood indicated that absence of the disease in the loblolly orchard prior to 1980 was not the result of a lack of inoculum. It is postulated that wounds on the loblolly trees caused by Hurricane Frederic in September 1979 provided a sufficient number of infection courts for the pitch canker fungus to initiate the epidemic.

Keyword(s): Pinus echinata, sporodochia.