The Expression of ABC and MFS Transporter Genes, Not Mutations at ScCyp51 , Is Associated with Difenoconazole Resistance in Stagonosporopsis Cucurbitacearum from Melon Fields

Stagonosporopsis cucurbitacearum is a main causal agent of gummy stem blight (GSB) in the melon field. Growers complain about the decreased control efficacy of DMIs for GSB in China recently. Difenoconazole (Dif) resistance frequencies reached 100% and 13.24% in S. cucurbitacearum isolates from Nanjing and Chongqing, respectively. Dif-sensitive isolates exhibited EC₅₀ values of 0.039-0.057 μg/mL and an MIC of 2 μg/mL, whereas Dif-resistant isolates showed EC₅₀ values