Cercospora arachidicola Hori is one of the most important foliar pathogens worldwide that limits peanut production in farmers' fields. Earlier screening trials allowed us to identify lines with field resistance to early leafspot. In order to determine the components of resistance of these lines and other lines reported to be resistant elsewhere, 19 peanut genotypes (Arachis hypogaea L.) were evaluated by the detached leaf technique using an isolate of Cercospora arachidicola from the ICRISAT Center in India. Significant differences were observed among genotypes for all components of resistance included in the study. With a few exceptions, early leafspot- resistant genotypes (ICG nos. 8298, 6902, 6284, 1703, 10900, 7878, 9989 and 10920) exhibited longer incubation periods, reduced sporulation, smaller lesion diameters and lower infection frequencies than susceptible lines. Genotypes ICG 8298 and ICG 6902 were the most resistant, while ICG nos. 221, 7827 and 6340 were the most susceptible to early leafspot. A few lines had resistant reactions to some components but susceptibility to others.
1Paper submitted as Journal article No. 1305 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).