Control efficacy of different fungicides and application technologies on southern corn rust
In recent years,southern corn rust,caused by Puccinia polysora Underw.,occurred with high frequency and serious harm in the corn producing areas of Huang-Huai-Hai.To clarify the optimal control period for southern corn rust,and analyze the control effects of different fungicides,application dosages and control frequency on southern rust corn,the following experiments were carried out.In the field conditions,the effects of different control periods and frequency on the control efficacy of southern corn rust and maize yield was investigated by using prothioconazole as the tested fungicide.At the same time,the effects of different dosages of propiconazole,tebuconazole,epoxiconazole,and prothioconazole on the control efficacy of southern corn rust and maize yield were also determined.The results showed that the control efficacy of early tasseling stage was the best(58.47％)and the yield increase rate was the highest(108.05％)among the flaring stage,early tasseling stage,spinning period and filling stage.The control effect of twice application on southern corn rust was significantly better than that of one application.Propiconazole,tebuconazole,epoxiconazole and prothioconazole all had certain control effects on southern corn rust.The control efficacies of 14 days after spraying were above 85％,and those of 28 days after spraying showed a significant downward trend.Four tested fungicides were used to control southern corn rust and epoxiconazole(1 350 mL/hm2)and prothioconazole(1 350 mL/hm2)had the best control effect.The control efficacies of 14 days after spraying were 95.68％and 95.57％,respectively,while those of 28 days after spraying were 55.39％and 60.27％,respectively.The recovered yield loss rates of the four fungicides at different dosages were over 70％.From multiple aspects such as control effect and the recovered yield loss rate,the optimal spraying fungicide period for controlling this disease was the early tasseling stage.The four tested fungicides could be used in field control.
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