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Resistance

Reaction of Field-Resistant Slash Pines to Selected Isolates of Cronartium quercuum f. sp. fusiforme. Charles H. Walkinshaw, Principal plant pathologist, U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station, Box 2008, GMF, Gulfport, MS 39503; Calvin F. Bey, principal plant geneticist, U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station, Box 2008, GMF, Gulfport, MS 39503. Phytopathology 71:1090-1092. Accepted for publication 9 February 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, 1981. DOI: 10.1094/Phyto-71-1090.

Nine isolates of Cronartium quercuum f. sp. fusiforme were pathogenic to 15 field-resistant slash pine (Pinus eliottii var. eliottii) families in greenhouse tests. Some isolates from random galls were as virulent as isolates derived from galls on a resistant family. Family × isolate interactions were significant in four experiments with 15 families but were greatly reduced when certain families were omitted from the analysis. Differences in gall incidence were generally significant among families but not among isolates.