Resistance to Cercosporidium Personatum Within Peanut Germplasm1

Abstract

Late leafspot, caused by Cercosporidium personatum, is prevalent in the southeastern United States and causes extensive defoliation and peanut yield losses if fungicides are not applied. Some sources of resistance to late leafspot have already been identified in the United States peanut germplasm collection. In screening 500 peanut plant introductions from the Southern Regional Plant Introduction Station, Experiment, Georgia, 33 genotypes with partial resistance to C. personatum were identified. These lines were evaluated for leafspot resistance and yield without fungicide protection from 1989 through 1991. Although PI 215695, PI 215696 and PI 215724 were significantly more resistant than all other genotypes over the three years, pod yields were low. During years of high disease severity, resistant selections PI 203396 and PI 162529 had the highest yields. Significant positive correlation occurred between late leafspot ratings and shelling percentage (r = 0.43 and 0.47) in 1990 and 1991. Evaluation of the main-stems of plants during the growing season revealed that the three most resistant genotypes had significantly less defoliation than Southern Runner, the only cultivar grown with resistance to late leafspot. There are important genes for resistance present in the United States peanut germplasm collection and there is a need for evaluation of the entire collection for useful resistance to leafspot and other pests.