Estimation of peanut yield losses due to early leaf spot in Oklahoma

Authors: DUFFECK, MAIRA - Oklahoma State University; DAMICONE, JOHN - Oklahoma State University; JACKSON, KENNETH - Oklahoma State University; Bennett, Rebecca; Chamberlin, Kelly

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/30/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: Early leaf spot, caused by the fungal pathogen Passalora arachidicola, is one of the most economically damaging diseases of peanut in Oklahoma. Quantifying yield losses associated with early leaf spot is essential to evaluate the effectiveness of current management strategies such as fungicides. To that end, analyses were conducted to assess the relationship between peanut defoliation caused by early leaf spot and peanut yield. Fungicide efficacy experiments conducted from 1990 and 2021 were mined for trials with significant levels of defoliation in the nontreated check. Fifty-three studies conducted over 25 years met the criteria of =40% defoliation and were included in the analysis. Results indicate that approximately 75% defoliation by early leaf spot reduces yield by 1,049 kg/ha in Oklahoma. In addition, yield losses due to early leaf spot were greater in low-yield than in high-yield environments. This information underscores the importance of deploying effective disease management strategies. USDA is an equal opportunity provider and employer.

Technical Abstract: Quantifying yield losses associated with important peanut diseases, such as early leaf spot (Passalora arachidicola), 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 early leaf spot (ELS) defoliation (%) and peanut yield (kg/ha) in Oklahoma (OK). Data were mined from fungicide efficacy trials performed in small plots across OK between 1990 and 2021. Fifty-three studies over 25 years met the criteria of ELS defoliation = 40% in the untreated check for inclusion in the analysis. Disease class (low defoliation = =76 and high defoliation = >76%) and yield class (low = = 2,976 and high = > 2,976 kg/ha) were included as categorical moderators. Since 45 studies were conducted with spanish market type cultivars and only eight with runner market type cultivars, the yield losses due to ELS defoliation were estimated using combined data from the two peanut market types. A random-coefficient model was successfully fitted to the data using maximum likelihood. The estimates of population-average of the intercept and slope were ß0 = 4,259.3 kg/ha (SE = 107.4) and ß1 = -13.4 kg/ha (SE = 0.7), respectively. A Wald-type test showed that including yield class in the model affected the estimation of the population-average intercepts but not the slopes. The estimated study-specific intercepts for the high and low yield classes were ß0 = 4,661.5 kg/ha (SE = 118.6) and ß0 –833.9 kg/ha (SE = 170.6), respectively, with a study-specific slope of ß1 = -14.0 kg/ha (SE = 1.0). Due to that, the calculated damage coefficients for high and low yield classes were -0.30% and -0.36%, respectively. These results indicate that yield losses due to ELS in OK are greater in low-yield environments than in high-yield environments. USDA is an equal opportunity provider and employer.