|Franke, M. - UNIVERSITY OF GEORGIA|
|Brenneman, T. - UNIVERSITY OF GEORGIA|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 25, 1999
Publication Date: N/A
Interpretive Summary: Diseases caused by Rhizoctonia solani lead to significant reductions in peanut yields and quality throughout the world. This study was conducted to develop screening techniques and to use these techniques to attempt to identify sources of resistant peanut germplasm. A subset of the peanut core germplasm collection consisting of 66 genotypes along with four commercial cultivars were evaluated for resistance to Rhizoctonia limb rot in field plots for two years. Resistance was estimated by counting and measuring stem lesions. Eleven core accessions representing the full range of disease expression were selected using this field data. These accessions and the commercial cultivars were evaluated in growth chambers for resistance to seedling infection. Unfortunately, there was not a significant correlation between resistance to limb rot in the field and the severity of seedling infection. Field data indicated six sources of resistance that can be used in the development of resistant cultivars.
Technical Abstract: Diseases caused by Rhizoctonia solani lead to significant reductions in peanut yields and quality throughout the world. A subset of accessions from the core collection of peanut germplasm plus the commercial cultivars Florunner, Southern Runner, Georgia Browne, and Georgia Green were evaluated for resistance to limb rot and seedling hypocotyl infections caused by R. solani. Georgia Green and core accessions 95 (PI 497351), 19 (PI 331326), 208 (PI 274193), 244 (PI 343361), 246 (PI 343398), and 524 (PI 288178) had a level of resistance comparable to Georgia Browne, the only commercial cultivar reported to have partial resistance to Rhizoctonia limb rot. Eleven core accessions, representing the full range of disease expression, and the commercial cultivars were evaluated in growth chambers for resistance to seedling hypocotyl infections and to determine if evaluating seedlings could serve as a primary screening method to identify potential sources of limb rot resistance. The most resistant core accessions to seedling hypocotyl infections were 234 (PI 159664) and 366 (PI 268968), and the most resistant commercial cultivar was Georgia Green. There was not a significant correlation between resistance to limb rot in the field and the severity of hypocotyl infections indicating that resistance to hypocotyl infections is not a good indicator of resistance to Rhizoctonia limb rot.