Effectiveness of benzimidazoles and strobilurin-triazole fungicide mixtures against Cercospora sojina

Abstract

Frogeye leaf spot (FLS), caused by Cercospora sojina, is an important soybean disease. The present study evaluated six Argentine isolates for their sensitivity to benzimidazoles (BZMs) and mixtures of quinone outside inhibitors (QoIs) with demethylation inhibitors (DMIs). In vitro, trifloxystrobin + cyproconazole and pyraclostrobin + epoxiconazole showed the lowest EC₅₀ values and were more effective than carbendazim. While the responses of isolates varied, the differences in sensitivity were not statistically significant. In vivo, the most and least sensitive isolates had distinct responses. Tri+Cyp effectively reduced the symptoms, which is consistent with in vitro data. The present findings reinforce the importance of monitoring C. sojina sensitivity to optimize its chemical control.