Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Early leaf spot (ELS), 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 to evaluate the effectiveness of currently deployed control strategies. In this study, a meta-analysis was conducted to assess the relationship between ELS defoliation and peanut yield of Spanish cultivars in Oklahoma. Data was recorded from fungicide efficacy trials performed across Oklahoma for 26 years, between 1990 and 2023. The results provide vital information and guidance to peanut producers and researchers in Oklahoma regarding modifying production practices and developing decision-making tools to mitigate losses due to ELS defoliation.

Technical Abstract: Early leaf spot (ELS), 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 ELS 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. Forty-nine studies over 26 years met the criteria of at least a 10% percentage point 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 ß ^_0 = 4,296.6 kg/ha (SE = 131.9) and ß ^_1= 13.7 kg/ha (SE = 0.9), respectively. The calculated damage coefficient for the disease-yield relationship for the Spanish market type peanut in Oklahoma was 0.32%. The economic damage threshold ranged from 11.1 to 100.0%, exemplifying how resilient the Spanish market type peanut varieties are to defoliation caused by ELS in Oklahoma. These results provide vital information and guidance to peanut producers and researchers in Oklahoma regarding modifying production practices and developing decision-making tools to mitigate losses due to ELS defoliation.