Control effect of chemical synergistic formula on pepper phytophthora blight

The toxicity of 9 fungicides against pepper phytophthora blight were tested with mycelium growth rate method. The results indicated that the highest toxicity of fungicides were dimethomorph(EC50=0.48 μg/mL) and fluopicolide(EC50=0.32 μg/mL). The synergisms were chosen by the method of co-toxicity coefficience, and the ratios were that chlorothalonil /fluopicolide(1∶9) and dimethomorph/fluopicolide(2∶8). The 20% suspension concentrates(SC) were prepared with best synergism ratio. After 10 d treatment, the pot experiment reuslts showed that the control effect of dimethomorph/fluopicolide 20% SC diluted 2 000 times was up to 96%; the control effect of chlorothalonil/fluopicolide 20% SC diluted1 000 times was 75%. Statistic analysis indicated that the control effect of dimethomorph/fluopicolide 20% SC diluted 2 000times was equal to dimethomorph 50% SC diluted 1 000 times and higher than that of 68.75% Infinito SC diluted 1 000times significantly.