Bio-activity Determination and Field Pesticide Effect Evaluation on Composition of Mefentrifluconazole and Kresoxim-methyl against Strawberry Powdery Mildew
In order to clarify the control effect and optimal complex ratio of mefentrifluconazole and kresoxm-methyl on strawberry powdery mildew,this experiment by pot-culture method determined the indoor bio-activity of mefentrifluconazole,kresoxm-methyl single dosages and their composition on strawberry powdery mildew;then based on the optimal synergistic ratio conducted field pesticide effect evaluation.The results showed that the LC50 values of single agents of mefentrifluconazole and kresoxm-methyl against strawberry powdery mildew were 0.416 8 and 2.673 7 mg·L-1,respectively.The mass ratio of the two showed a synergistic effect in the range of 3:7-6:4,the synergistic effect was the most significant when compound ratio was 4:6,the cotoxicity coefficient was 149.Based on this mass ratio,the composition of 400 g·L-1 mefentrifluconazol SC and 50％kresoxm-methyl WC showed the best prevention and control effect at the dosage of 25 g·(667 m2)-1,and field efficacy on strawberry powdery mildew was 78.67％,87.00％,and 91.07％,respectively,7 days after the first,second,and third application.
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