Detection Of Resistance Of Botrytis Cinerea From Shandong Province To Common Fungicides And Sensitivity To Isopyrazam And Tetramycin

Gray mold is one of the most important diseases of greenhouse in China, and has caused significant losses. Currently, chemical control is still the mainly method to control of gray mold. However, with the widely using of pesticides, the resistance of B. cinerea has been standing out increasingly. Isopyrazam and tetramycin are novel fungicides. But they have not been used in China. In order to provide the basis for using in field, 82 B.cinerea isolates, collected from different areas of Shandong Province, were determine the sensitivities to commonly used fungicides using the mycelium growth rate method. In addition, we have studied the biological activity of isopyrazam and tetramycin against B.cinerea, analysized of the cross-resistance patterns between isopyrazam, tetramycin and other commonly used fungicides, and field efficacy trials of isopyrazam and tetramycin on gray mold.1. The highly resistance frequency of B.cinerea from Shandong province to carbendazim was 86.42%, and sensitive isolates accounted for 1.23%; resistance frequency to pyrimethanil was 83.93%, and highly resistant isolates accounted for 60.71%; resistance frequency to procymidone was 85.29%, and lowly resistant isolates accounted for 67.65%; resistance frequency to iprodione was 81.16%, and lowly resistant isolates accounted for 50.72%; resistance frequency to diethofencarb was 95.52%, lowly resistant isolates accounted for 74.63%; resistance frequency to boscalid was 62.35%; resistance frequency to fluopyram was more than 50%, and lowly resistant isolates accounted for 41.30%, sensitive isolates accounted for 38.04%; sensitive resistance frequency to fludioxonil was 92%, highly resistant isolates just accounted for 2%; resistance frequency to pyrisoxazole was 81.25%, lowly resistant isolates accounted for 76.56%.2. Isopyrazam had strong activity against the germ tube elongation, spore germination and mycelial growth of B.cinerea. Frequency distributions of isopyrazam EC50 values were unimodal curves with mean EC50 values of 0.07 ± 0.04(s.d.) and 0.68 ± 0.36 ?g·m L-1 for the inhibition of spore germination and mycelial growth, respectively. In addition, there was no positive multiple resistance between isopyrazam and other classes of botryticides, such as diethofencarb, iprodione, pyrimethanil or pyrisoxazole. In field trials conducted during 2014 and 2015, isopyrazam used at a concentration of 150 and 200 g a.i. ha-1 provided a control efficacy ranging from 76.7 to 87.8% on leaves and from 81.5 to 90.7% on fruit. These results suggest that isopyrazam has the potential to play an important role in the management of gray mold.3. The baseline sensitivities showed that the frequency distributions of tetramycin were unimodal curves, with mean EC50 values of 0.020 ± 0.009 and 0.35 ± 0.20 ?g·m L-1 for the inhibition of spore germination and mycelial growth, respectively. Tetramycin had no cross-resistance with other fungicides tested. In field trials performed in Tai'an city, Shandong province in 2014 and 2015, tetramycin 60 g a.i. ha-1 provided high efficacy on gray mold. These results showed that tetramycin may serve as an alternative fungicide for the control of gray mold.