Resistance Identification of Pepper Germplasm Resources Against Phytophthora capsici and Drug Sensitivity Analysis in P.capsici

Twenty-seven pepper germplasm resources were evaluated by the method of irrigating the root though zoospore,in order to screen pepper germplasm resources resistant to P.capsici.The results showed that 3 of 27 pepper lines were highly resistant to P.capsici,which were 11% of the tested lines.The most resistant line was L151 and the disease index was 2.86.The second resistant line was L19 and the disease index was 5.71.Six of 27 lines were resistant against P.capsici,which were 22% of the tested lines.And the disease index varied from 10.00 to 30.00.Fifteen of 27 lines were susceptible to P.capsici,which were 56% of the tested lines.To test the drug sensitivity in P.capsicito fluazinam and cyazofamid,the mycelial growth inhibition rate of 7 P.capsici isolates grown on medium added fluazinam and cyazofamid were measured.The mycelial growth inhibited by fluazinam varying from 42.68%to 71.85%,whereas inhibited by cyazofamid varying from 1.87%to55.01%.Cyazofamid had the lowest inhibition rate on isolate P5,which was only 1.87%.And on other two isolates P1 and P2,the inhibition rate of cyazofamid was relatively low as well,i.e.22.38% and37.50%,respectively.The results indicated that part of the tested P.capsici isolates had chemical drug resistance risk against cyazofamid with different level.