Estimation of Peanut Yield Losses Due to Early Leaf Spot on Spanish Cultivars in Oklahoma: A 26-year Summary.

Abstract

Early leaf spot, caused by Passalora arachidicola, is the most prevalent and yield-limiting foliar disease affecting peanuts in Oklahoma. Quantifying yield losses associated with end-of-season defoliation caused by early leaf spot is essential to evaluate the effectiveness of currently deployed control strategies. To that end, a meta-analysis was conducted to assess the heterogeneity in the relationship between ELS defoliation (%) and peanut yield (kg/ha) of Spanish cultivars (A. hypogaea ssp. fastigiata var. vulgaris) in Oklahoma. Data were mined from fungicide efficacy trials performed in small plots across Oklahoma between 1990 and 2023. Studies (n=49) over 26 years met the criteria of at least a 10% difference between the minimum and maximum defoliation within the study. A random-coefficient model was successfully fitted to the data using maximum likelihood. The estimates of population-average of the intercept and slope were β ̂_0 = 4,296.6 kg/ha (SE = 131.9) and β ̂_1= 13.7 kg/ha (SE = 0.9), respectively. The damage coefficient, which represents the percentage reduction in yield per percentage point increase in crop defoliation, was 0.32%. These results allow the prediction of yield loss given for end-of-season defoliation levels and guide peanut producers and researchers in Oklahoma regarding modifying production practices and developing decision-making tools to mitigate losses due to early leaf spot defoliation.