Disease Progress of Early Leaf Spot and Components of Resistance to Cercospora arachidicola and Cercosporidium personatum in Runner-Type Peanut Cultivars

This study assessed components of resistance for three runner-type peanut cultivars to infection by Cercospora arachidicola (Ca) and Cercosporidium personatum (Cp), the causal organisms of early leaf spot and late leaf spot, respectively. Resistance components were compared to disease resistance observed in the field. A field study monitored the progression of leaf spot incidence and severity in peanut cultivars Georgia Green, Georganic, and DP-1. Time of disease onset (TDO) and temporal epidemic rate (rate) were estimated for incidence with the logistic model, and for severity with the linear model. Early leaf spot was the predominant disease in the field. Estimates of TDO were 9 d later for DP-1 than for Georgia Green, based on incidence models, and 6 and 7 d later for Georganic and DP-1 than for Georgia Green, respectively, based on severity models. Incidence progression rate was highest for Georganic in 2002 and Georgia Green in 2003, while severity progression rate was highest for Georgia Gr...