Screening And Application Of Wheat Scab Control Agents

Wheat scab is known as wheat cancer.In recent years,the incidence of wheat scab has increased year by year,and it has developed resistance to traditional control agents such as carbendazim.At present,the control situation is not optimistic.Traditional single preparations such as Carbendazim and metconazole have poor control effect on wheat scab.The resistance of strains to carbendazim is widespread,and it is urgent to develop new pesticides with good control effect and low residue.In this study,19 different concentrations of pesticides were sprayed during the flowering stage of wheat,the scale of wheat scab and the control effect were counted 7 days and 15 days later to select effective pesticides.For the drug with good control effect,the wheat grain was harvested 45 days after the application.,and the residue analysis was carried out by gas chromatography and liquid chromatography to determine whether the residue amount meets the national and international standards.The results showed that the control effects of carbendazim wettable powder 75 g/667 m2,carbendazim wettable powder+acid regulator 50+20 g/667 m2 and carbendazim wettable powder 50 g/667 m2 were 60.2%,60.4%and 55.4%,respectively.The control effects were poor and the resistance of Fusarium to carbendazim was widespread.The control effects of prothioconazole-tebuconazole suspeinsion(manufacturer A)at 16 g/667 m2,difenoconazole and propiconazole+carbendazim suspension at 6+75 g/667 m2 were 89.8%and 89.8%,respectively.Among the 19 agents,prothioconazole-tebuconazole suspension(manufacturer A)at 20 g/667 m2 and difenoconazole-propiconazole+carbendazim suspension at 9+75 g/667 m2 had the best control effect(82.98%and 85.82%)(P>0.05,no statistical difference).Drug residues of tebuconazole,carbendazol,difenoconazole,propiconazole,prothioconazole and prothioconazole-desthio were detected in wheat grains.The residues were<0.01,0.064,0.0162,<0.005,<0.005 and<0.005 mg/kg in wheat grains harvested in 2017,and<0.01,0.072,0.0248,<0.005,<0.005 and<0.005 mg/kg in wheat grains harvested in 2018,respectively.The residue data obtained in the past two years meet the national and international maximum residue limits(MRL)requirements.For carbendazim-resistant strains,prothioconazole-tebuconazole suspension 16 g/667 m2.difenoconazole and propiconazole+carbendazim suspension 6+75 g/667 m2 were recommended for the control of wheat scab in the younger epidemic years,prothioconazole-tebuconazole suspension 20 g/667 m2,difenoconazole-propiconazole+carbendazim suspension 9+75 g/667 m2 were recommended for the control of wheat scab in the heavier epidemic years.