Detection and comparison of fungicide resistance in Botrytis fabae and B.cinerea causing broad-bean chocolate spot disease

Disease samples of broad-bean chocolate spot (BBCS) from Zhejiang,Hubei and Anhui provinces were collected to isolate and identify the pathogens.Resistance of Botrytis fabae and B.cinerea which cause BBCS to fungicides was detected through the mycelial growth rate method.And the fungicide resistance risk of B.fabae and B.cinerea was assessed in vitro.Results showed that a total of 153 isolates were collected and 122 of them were B.fabae with the frequency of 79.7%.The rest 31 isolates were B.cinerea with the frequency of 20.3%.Thirty-seven high-level carbendazim resistance isolates (9 of them were B.fabae) and 42 low-level iprodione resistance isolates (17 of them were B.fabae) were detected.The EC50 values of pyrimethanil ranged from 0.01 to 5.13 μg/mL with a mean value of 0.72±0.15 μg/mL.These results indicated that BBCS developed resistance to common fungicides and more serious resistance was developed in B.cinerea than in B.fabae. Moreover,results suggested that the resistance risk of B.cinerea was significantly higher than that of B.fabae in vitro.