Detection Of Resistance Of Botrytis Cinerea From Shandong Province To Common Fungicides And Sensitivity To Triflumizole And Fluazinam

Gray mold, caused by Botrytis cinerea Pers.:Fr.(teleomorph Botryotinia fucke-liana), is one of the most important diseases of greenhouse vegetable crops in Northern China, causing significant yield losses. Currently, the control of gray mold is mainly based on chemical control. However, the resistance of B. cinerea to registered fungicides such as carbendazim, procymidone, iprodione, diethofencarb and pyrimethanil has been frequently reported. Triflumizole and fluazinam are the novel fungicides with new modes of action to B.cinerea. So far they have not been used widely in China. In order to provide the basis for field spraying, the mycelium growth rate method was used to determine the sensitivities of 79 B.cinerea isolates from different areas of Shandong Province to commonly used fungicides. In addition, we undertook the studies on testing the biological activity of triflumizole and fluazinam against B.cinerea, detection of sensitivity of B.cinerea to triflumizole and fluazinam, analysis of the cross-resistance patterns between triflumizole, fluazinam and the other fungicides with different modes of action to B.cinerea and field efficacy trials of triflumizole and fluazinam on gray mold. The main results are listed as follows:1. The total resistance frequency of B.cinerea from Shandong province to carbendazim was 94.94%, and highly resistant isolates accounted for 88.61%; resistance frequency to procymidone was 82.28%, and lowly resistant isolates accounted for 64.56%, and no highly resistant isolates were detected; resistance frequency to iprodione was 70.89%, and lowly resistant isolates accounted for 68.43%, and no highly resistant isolates were detected; resistance frequency to diethofencarb was 89.87%, and lowly resistant isolates accounted for 56.96%, highly resistant isolates accounted for 32.91%; resistance frequency to pyrimethanil was 81.01%, highly resistant isolates accounted for 63.29%; resistance frequency to SYP-Z048 was 12.66%, and 9 isolates showed lowly resistant, 1 isolates showed moderately resistant, and no highly resistant isolates were detected; resistance frequency to boscalid was 7.59%, and 4 isolates showed lowly resistant, 2 isolates showed moderately resistant, and no highly resistant isolates were detected. B.cinerea isolates resistant to boscalid had good stability.2. Triflumizole had strong activity against the mycelial growth and germ tube elongation of Botrytis cinerea. Compared with mycelial growth, spore germination of B. cinerea was less sensitive to triflumizole. The frequency distribution of the EC50 values was a unimodal curve, and the values ranged from 0.1494 to 1.4927 μg m L-1, with a mean value of(0.5782 ± 0.2453) μg m L-1. At the highest concentration of triflumizole tested(i.e., 200 μg m L-1), the efficacy of the protective and curative effect reached 89.09% and 91.08%, respectively. The sensitivity to triflumizole was plotted against the sensitivity to carbendazim, iprodione, diethofencarb, pyrimethanil, SYP-Z048 and boscalid, and the result showed that sensitivity to triflumizole was correlated with sensitivity to SYP-Z048, but not to the other botryticides. The results of field efficacy trials showed that the control efficacy of triflumizole on pimento gray mold when used at the rate of 150 a.i. g hm-2 was above 84%, which was higher than the control efficacy of boscalid at the rate of 300 a.i. g hm-2. Hence, triflumizole can be used to control gray mold.3. Fluazinam had strong activity against the mycelial growth, spore germination and germ tube elongation of Botrytis cinerea, especially inhibited spore germination. The frequency distribution of the EC50 values was a unimodal curve, and the values ranged from 0.0029 to 0.0412 μg m L-1, with a mean value of(0.0154 ± 0.007) μg m L-1. At the concentration of 5μg m L-1, the efficacy of the protective effect of fluazinam reached 100%, exhibited excellent protective effect. There were no cross-resistance between fluazinam and other botryticides. The results of field trials showed that the control efficacy of fluazinam at the rate of 300 a.i. g hm-2 on pimento gray mold was higher than the control efficacy of all the control fungicides, which indicated that fluazinam could play a vital role in the management of gray mold.