Abstract:

In order to evaluate the resistance risk of Rhizoctonia solani to hexaconazole the sensitivity of 101 R. solani strains to hexaconazole using mycelium growth rate method, which isolated from 7 rice areas of Guizhou, Hubei, Hunan and Henan Provinces, and the baseline sensitivity of R. solani to this fungicide was also established. The results showed that the EC₅₀ of hexaconazole to R. solani in different rice areas was 1.0751 to 2.9228 mg/L, with a mean of 1.8081 mg/L, and the sensitivity differences strains were 2.72 times. The frequnecy of sensitivity was in approximately normal distribution(W=0.980,P=0.157>0.05), and the mean EC₅₀ values could be used as the baseline sensitivity of R. solani to hexaconazole, and therefore the mean EC₅₀ values was used as the baseline sensitivity of R. solani to hexaconazole, and the resistance monitoring during 2016-2018 of R. solani showed that the R. solani strain was still sensitive to hexaconazole. The results of this study provide references for field medication.

Key words: Rhizoctonia solani, hexaconazole, baseline sensitivity, resistance monitoring