Description

Abstract: Early Leaf spot {caused by Cercospora arochidirola) was monitored in isolated ficld plots of 20 Virginia-type peanut (Arachis hypogueo) lines in 1982- 1984. Increases in the percentage of diseased leancrs and percent defoliation lit the Gompertz model more closely than the logistic or monamolecular models. Rates of increase in leaf spot incidence and defoliation as well as areas under disease progress curves (AUDPCs) varied among peanut genotypes. Peanut genotypes with larger AUDPCs had Iastcr rates of disease increase. Florlgiant. NC 2. and selected lines from crosses of NC 5 X Florigiant and crosses of NC 2 X NC 5 were more susceptible toearly leaf spot than the otherentries tested. CP-NC 343and a selected line from GP-NC 343 X NC 5 exhibited the lowcst d~sease level%. Discase levels at 103-1 IOdaysatterplanting contributed most to hU DPCs AtlDPCs were more highly correlated with laten[ period. percent lesions sporulating, spore product~ona, nd time to dcfol~ationt han were infection and defoliation rates. The maximum percentage 01 lesions that sporulated was the resistance component most highly carrctatcd with disease progresv in the field.