Baseline sensitivity of Blumeria graminis f.sp.tritic to metrafenone, quinoxyfen and bioactivitives of these fungicides

The sensitivity of 53 Blumeria graminis f.sp.tritic(Bgt) strains to metrafenone and quinoxyfen were determined by leaf segment assay.The results showed that the mean EC50 values is (0.001 9±0.0006) mg/L for metrafenone and (0.013 1±0.002) mg/L for quioxyfen;The sensitivity of Bgt to metrafenone was significantly lower than that of quinoxyfen,suggesting metrafenone has higher intrinsic activity on Bgt;Tradimefon showed no cross-resistance with metrafenone and quinoxyfen(R2=0.102 6,0.491 9,respectively).The curative and preventive activities of the two fungicides on Bgt in wheat were evaluated.With metrafenone and quinoxyfen fungicides treatments 1 days after inoculation and 1 days before inoculation,the efficacy of preventive and curative efficacy of the two fungicides were 92.21% and 84.25%,82.43% and 70.25%,respectively.Suggesting both fungicides had good curative and preventive properties.