Sensitivity of Colletotrichum plurivorum and C. truncatum isolated from soybean in Brazil to SDHIs and DMIs fungicides

Anthracnose disease caused by Colletotrichum species has resulted in increased economic losses on soybean fields in Brazil. For the disease management, fungicide is the main disease control strategy used. Recently, variations in field performance of fungicides on anthracnose have been observed and were speculated to be a result of distinct Colletotrichum species occurring in the fields. Therefore, this study aimed to identify the species occurring in the sampled soybean fields and evaluate the sensitivity of 30 Colletotrichum samples collected from 2021 and 2022 seasons to benzovindiflupyr (BVF), fluxapyroxad (FXD), inpyrfluxam (IPFX), difenoconazole (DFZ), prothioconazole (PTZ) and mefentrifluconazole (MFTZ). Twenty-three samples were identified as C. plurivorum and seven samples were identified as C. truncatum based on molecular analysis. The SDHI fungicide BVF, and DMIs DFZ and PTZ, showed higher fungitoxicity against C. plurivorum and C. truncatum than the other fungicides tested. BVF showed the same intrinsic activity on both C. plurivorum and C. truncatum . To our knowledge, this is the first study reporting the sensitivity of Colletotrichum species to six fungicides and showed the C. plurivorum and C. truncatum tested samples were more sensitive to BVF, PTZ, and DFZ than to FXD, IPFX, and MFTZ . These results add important information for anthracnose and anti-resistance management on soybean using SDHI and DMIs fungicides.