Estimation of Peanut Yield Losses Resulting From Early Leaf Spot on Spanish Cultivars in Oklahoma: A 26-Year Summary

Early leaf spot (ELS), caused by <i>Passalora arachidicola</i>, is the most prevalent and yield-limiting foliar disease affecting peanuts in Oklahoma. Quantifying yield losses associated with end-of-season defoliation caused by ELS is essential for evaluating 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 (percentage) and peanut yield (kilograms/hectare) of Spanish cultivars (<i>Arachis</i> <i>hypogaea</i> ssp. <i>fastigiata</i> var. <i>vulgaris</i>) in Oklahoma. Data were mined from fungicide efficacy trials performed in small plots across Oklahoma between 1990 and 2023. Studies (<i>n</i> = 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 [Formula: see text] = 4,296.6 kg/ha (SE = 131.9) and [Formula: see text] = 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 resulting from ELS defoliation.