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Genetics

Diallel Analysis of Genetic Resistance to Cronartium quercuum f. sp. fusiforme in Slash Pine. Margene M. Griggs, Plant geneticist, Southern Forest Experiment Station, U.S. Department of Agriculture, Forest Service, P.O. Box 2008, GMF, Gulfport, MS 39503; Charles H. Walkinshaw, principal plant pathologist, Southern Forest Experiment Station, U.S. Department of Agriculture, Forest Service, P.O. Box 2008, GMF, Gulfport, MS 39503. Phytopathology 72:816-818. Accepted for publication 13 November 1981. 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, 1982.. DOI: 10.1094/Phyto-72-816.

Selfed, intercrossed, and wind-pollinated progenies of five slash pines of varying field resistance were inoculated with three collections of Cronartium quercuum f. sp. fusiforme. Two collections were from individual galls while the third was a composite from 10 galls. Differences among families and inocula occurred in percent galled seedlings 9 mo after inoculation. In diallel analyses, general combining ability effects were significant while specific combining ability effects were not. Maternal effects were not apparent. Gall lengths were not significantly different among full-sib families or inoculum sources. The two most resistant parents appear to possess different kinds of resistance.