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TECHNICAL SESSION: Chemical Control

Reducing chlorothalonil use in Peanut disease management

Monday, August 4, 2025
2:15 PM - 2:30 PM HST
Location: Room 313 A
Abstract Text:

Peanut (Arachis hypogaea L.) is one of the most economically important food crops grown in the southeastern US, which was valued at $1.3 billion dollars in 2024. Early leaf spot (Passalora arachidicola) and late leaf spot (Nothopassalora personata) are two detrimental foliar fungal diseases of peanuts, which occurs worldwide and can cause yield losses of up to 50% if not controlled. Leaf spot diseases are managed through rigorous fungicide programs, which typically contain two to seven applications of chlorothalonil. However, recent regulatory decisions have limited its use in agriculture. Thus, the goal of this study was to assess alternatives to chlorothalonil (copper sulfate, dodine, and sulfur) for leaf spot control to reduce its usage in peanuts and maintain yields. From 2021 to 2024, 8-12 alternative fungicide spray programs were arranged in a randomized complete block design on a susceptible cultivar, ‘GA-16HO’, in southeast Alabama. Under low disease pressure, all fungicide programs provided statistically similar leaf spot control to chlorothalonil alone. However, dodine alone and dodine + penthiopyrad did not significantly decrease leaf spot severity when compared to the nontreated control under high disease pressure. In contrast, copper sulfate + sulfur significantly reduced leaf spot severity when compared to the nontreated control regardless of disease pressure. These results indicate that are copper sulfate + sulfur and dodine are viable options to reduce the use of chlorothalonil in peanuts.