| In order to investigate the control efficacy of different fungicides on Fusarium head blight(FHB) and deoxynivalenol(DON) contamination in wheat grain, the indoor toxicity of six fungicides to F.asiaticum was detected in dividually,and the digestion dynamics of the six fungicides sprayed once and twice on wheat spikes were detected and analyzed by using ultra-performance liquid chromatography-tandem massspectrometry(UPLC-MS/MS)method. The field control tests of the six fungicides sprayed once and twice on FHB and DON contamination in wheat grain were conducted.The results showed that the degree of in hibition of the six fungicides on the mycelial growth of F.asiaticum were presented as follows:prochloraz>tebuconazole>phenamacril>pydiflumetofen>pyraclostrobin>azoxystrobin. The degradation dynamics of the six fungicidesin wheat spikes were conformed to the first-order kinetic equations.The half-lives of 50% prochloraz WP,430 g·L-1 tebuconazole SC,25% phenamacril SC, 200 g·L-1 pydiflumetofen SC, 250 g·L-1 pyraclostrobin EC and 250 g·L-1 azoxystrobin SC sprayed once on wheat spikes were 2.081 5, 3.094 4, 2.365 7, 3.026 8, 3.209 0 and 3.136 4 days, respectively,and 2.044 7, 3.332 4, 2.529 7, 3.397 8, 3.300 7 and 3.179 6 days under twice spray, respectively. The results of field trials showed that the FHB disease index(DI) control efficacy of 200 g·L-1 pydiflumetofen SC sprayed once and twice were 85.96% and 94.88%, and the DON control efficacy were 81.43%and 88.91%,respectively.The DI control efficacy of 430 g·L-1 tebuconazole SC, 25% phenamacril SC and 50% prochloraz WP sprayed once and twice were 61.48%-73.62% and 75.33%-86.15%,and the DON control efficacy were 53.88%-69.70% and 60.09%-79.45%,respectively.The DI control efficacy of 250 g·L-1 pyraclostrobin EC and 250 g·L-1 azoxystrobin SC sprayed once were 63.76% and 50.47%, and the DON control efficacy were 41.03% and -28.95%,respectively.The DI control efficacy of 250 g·L-1pyraclostrobin EC and 250 g·L-1 azoxystrobin SC sprayed twice were 79.51% and 61.10%, and the DON control efficacy were 52.75% and -18.08%,respectively.Pydiflumetofen provided best control efficacy on FHB and DON contamination in wheat grain among different fungicides. However, pyraclostrobin and azoxystrobin provided weak control efficacy on FHB and DON contamination in wheat grain, and even increased DON contamination. This study provides a scientific basis for the chemical control of FHB and DON contamination in wheat grain. |
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