Preparation Of 6% Thiram-Tebuconazole Powder For Dry Seed Treatment Appropriative Of Wheat Seed

Based upon the production situations of the pests in wheat crops in china, it is very important to prepare a new powder for dry seed treatment (DS) formulation that could be used to comprehensively control the soil-borne and seed- borne diseases such as wheat head smut (Ustilago tritici) and sheath blight (Rhizoctonia solani) with the reasonable cost.Firstly, joint toxicity of binary mixture of thiram and tebuconazole at following five different ratios such as 3.3:2.5, 4:2, 4.5:1.5, 5:1 and 5.5:0.5 was tested against several crop pathogens. Rcsults showed that the mixture of thiram and tebuconazole had an obvious synergism, which the combination of 4.5:1.5 exhibited the most significant synergism with the co-toxicity coefficient of 155. and could be considered as the optimal colnbination ratio of thiram and tebuconazole.Secondly, a mixture powder for dry seed treatment formulation of thiram and tcbuconazole was prepared based upon joint toxicity to the crop pathogens. 6% DS formulation was selccted as the active ingredient according to optimal ratio of thiram and tebuconazole (4.5:1.5). Proper carriers and fillers, surfactants, wetter, dispersants and extenders were added, mixed and formulated into the desired product forlnulation. 6% thiram-tebuconazole DS could be manufactured based upon fhe existing production processes of corn and cotton DS.Thirdly. deterlnination of active ingredient thiram and tebuconazole was carried out by high performance liquid chromatography. Results showed that recovery of thiraln and tebuconazole in samples yvas 99.8% and 100%, and coefficient of variation was 1.07% and 1.38%. indicating that the product met the requirement issued by Ministry of Agriculture. In addition, the product was low toxic to rats.Finally, field trials of 6% thiram-tebuconazole DS is against the wheat head smut had been investigated in Hebei, Inner Mongolia, Heilongjiang and Henan province and regions for two years. Results showed that 6% thiram-tebuconazole DS had an control efficacy of 88.3%～99.22% against the wheat head smut. 63.9%～93.19% against the wheat sheath blight, and no phyto-toxicity to wheat crops.At present the product 6% thiram-tebuconazole DS is registered for control of the wheat head smut approved by ICAMA, and shows apromising economical, social and ecological benefits.