Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: April 4, 2004
Publication Date: June 4, 2004
Citation: Carson, M.L. 2004. Does the species concept matter in breeding for resistance? the maize gray leaf spot experience. Phytopathology. Technical Abstract: Gray leaf spot (GLS) has become a serious disease of maize throughout the U. S. and much of the world. GLS resistant hybrids have been developed commercially based on field screening. At least three species of Cercospora have been associated with GLS; two sibling species of C. zeae-maydis and C. sorghi var. maydis. When isolates of these three species were tested for pathogenicity on a set of maize hybrids in field trials, there was no significant difference in pathogenicity between the two sibling species of C. zeae-maydis. There were no hybrid x sibling species interactions, as hybrids resistant to one species were resistant to the other. There were, however, significant isolate X hybrid interactions within each of the two sibling species, which resulted from significant variation in aggressiveness within each species. Less aggressive isolates were less effective in discriminating levels of resistance among the hybrids than more aggressive isolates. Isolates of C. sorghi var. maydis tested were not pathogenic, but appeared to be effective saprophytes.