Exploring mechanisms of resistance to dimethachlone in Sclerotinia sclerotiorum

This study demonstrates that resistance to dicarboximide fungicide dimethachlone in S. sclerotiorum is emerging in China. Several fitness parameters, including mycelial growth rate, sclerotia formed in vitro, aggressiveness on leaves and osmotic and H2 O2 sensitivity, indicate that the resistant strains may not effectively compete with sensitive isolates in the field in the absence of selection pressure. Lost expression or the V238A point mutation in the SsOs1 gene may confer resistance to dicarboximide fungicide dimethachlone in S. sclerotiorum, but this study illustrates that other, yet unknown mechanisms also exist.