Resistance to Late Leafspot Peanut of Progenies Selected for Resistance to Early Leafspot1

Abstract

Fifty-six F7 peanut (Arachis hypogaea L.) lines previously selected for resistance to early leafspot (Cercospora arachidicola Hori) were evaluated in the field and greenhouse for resistance to late leafspot [Cercosporidium personatum (Berk. & Curt.) Deighton]. After growing in field plots for 12 weeks, differences for numbers of lesions per 15 leaves were found among the lines and between these lines and NC 3033, the susceptible control. Eleven lines with the fewest numbers of lesions and their parents were screened in the greenhouse for components of resistance. These lines had lesions that were significantly smaller, produced lesions with longer latent periods, and produced fewer conidia than NC 3033. Latent periods ranged from 23 to 26 days for the selections compared to 20 days for NC 3033. GP-NC 343 and NC 5 were the most resistant parents with latent periods of 24 days each. A rank correlation of greenhouse and field data revealed that the rank of an entry in the greenhouse for latent period, lesion area and amount of sporulation was correlated with the rank of the entry in the field. Thus, these variables could be used as measurements of resistance to predict the performance of a line in the field for this population. Lines with resistance to late leafspot can be selected from a population of lines with this parentage which have been selected for resistance to early leafspot.