| Fusarium head blight(FHB)which occur in each growth period of wheat,seriously affected the yield and quality of wheat.Chemical control is an important means to prevent and control FHB,but it has some inadequacies,the germs produced resistance or drug resistance because of the continuous use of these chemical agents in the field.The study is based on a new type of high efficiency and broad-spectrum fungicide,prothioconazole.Prochloraz,pyrazole azoxystrobin,triclopyricarb,boscalid,metconazole,methylene(bis)thiocyanate and carbendazim were selected as screening agents.The toxicity of seven fungicides against Fusarium graminearum was compared by mycelium growth rate.High efficiency single fungicide,prochloraz,was selected for compound study,and the best ratio of compound was determined.The oil suspension concentrate was prepared by using prothioconazole and prochloraz as effective components,and the field efficacy test was carried out.The main contents are as follows:1.In the laboratory conditions,Fusarium graminearum(PH-1)was used as the test pathogen,and the mycelium growth rate method was used to determine the toxicity of prochloraz,pyrazole azoxystrobin,triclopyricarb,boscalid,metconazole,methylene(bis)thiocyanate and carbendazim.The test results showed that the toxicity of seven fungicides to Fusarium graminearum was in the order from high to low: prochloraz(0.098?g/mL),metconazole(0.104?g/mL),pyrazole azoxystrobin(0.173?g/mL),carbendazim(0.637?g/mL),methylene(bis)thiocyanate(3.927?g/mL),triclopyricarb(4.044?g/mL),boscalid(7.246?g/mL).So,prochloraz was selected to compound with prothioconazole.Based on Horsfall methods,we did qualitative analysis on synergistic action of two composite bactericides.The results showed that,C value of composite bactericides is stable for Fusarium graminearum,and all the C values are higher than 1;on interval of proportion 3:7-1:9,the C values are higher than 1.2 and it shows the synergistic actions.Considering of economic benefit and the synergistic actions analysis,the proportion(mass percentage)of prothioconazole and prochloraz to control Fusarium graminearum,was determined to be 4:3 and 4:1.2.Through the screening of solvents,emulsifying dispersant and viscosity modifier,the final formulation of the 30% prothioconazole-prochloraz oil dispersion ratio of 4:3 and 4:1 was determined.(1)17% prothioconazole,13% prochloraz,4% Nong Ru 601#,4% EL-20,2% calcium dodecylben-zenesulfonate,0.75% magnesium aluminum silicate,methyl oleate make up to 100%;(2)24% prothioconazole,6% prochloraz,5% Nong Ru 603 #,7% A-115,2% calcium dodecylben-zenesulfonate,0.6% magnesium aluminum silicate,methyl oleate to make up to 100%.Based on this,the physicochemical indexes of two proportional preparation samples were tested.All have reached the relevant quality control index requirements for oil suspension pesticide products.3.To evaluate the control effect of prothiooxacin,prochloraz and 30% prothioconazole-prochloraz oil dispersion on DON toxicity with HPLC-MS in the Laboratory,compared with the fungicide JS399-19.The test results show that the two proportions of 30% prothioconazole-prochloraz oil dispersion can reduce the production of DON from FHB,but there was no significant difference in the production of DON per unit of mycelium compared with the single dose of prothioconazole and prochloraz.4.According to the field efficacy test criteria,field efficacy tests were conducted on the two 30% prothioconazole-prochloraz oil dispersion samples.The results showed that the two 30% prothioconazole-prochloraz oil dispersions developed had a slightly higher control efficacy than the 25% JS399-19 suspensions currently used in production.Comprehensive control effect and economic factors,determined that the two kinds of 30% prothioconazole-prochloraz oil dispersion developed as a good agent for the control of FHB,has a good application prospect. |
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