Dodine as an alternative to chlorothalonil in the control of leaf spot diseases in peanut

Peanut (Arachis hypogaea L.) is susceptible to leaf spot diseases caused by the fungi Nothopassalora personata and Passalora arachidicola, which can decrease yield substantially. Chlorothalonil is one of the most widely used fungicides to control these diseases but was recently banned in the European Union due to toxicity to amphibians and fish. Dodine is an alternative fungicide with a similar range of activity. However, information about its impact on the peanut physiology is lacking. The objectives of this study were to assess the effect of dodine on leaf photosynthesis, yield, and pod quality of peanut and evaluate the potential of dodine as a replacement of chlorothalonil in the control of leaf spot diseases. A 3-year field experiment was conducted using Georgia-06G. Treatments consisted of chlorothalonil at 0.86 kg a.i. ha⁻¹ (high rate), chlorothalonil at 0.43 kg a.i. ha⁻¹ (low rate), dodine at 0.68 kg a.i. ha⁻¹ (high rate), and dodine at 0.34 kg a.i. ha⁻¹ (low rate). Photosynthetic efficiency was altered by fungicide in only a few instances, and a clear trend was not observed. The high rate of dodine resulted in the least defoliation caused by leaf spot of all fungicide treatments. Pod maturity, yield, and grading parameters were not affected by fungicide. Overall, dodine did not impact negatively the photosynthetic activity, pod quality, and yield of peanut. Moreover, this chemistry was efficient in controlling leaf spot diseases under heavy disease pressure; therefore, dodine is a potential replacement of chlorothalonil in the control of leaf spot diseases in peanut.