New Pesticide Screening to Control Potato Late Blight and Its Economic Benefit Evaluation

From 2009 to 2010,the contrast test of the effect of 15 new fungicides on its yields,times of spray,mixture at the 6 counties of Sichuan were conducted to control potato late blight in the fields.The results showed that the best control effects to potato late blight were 687.5 g/L Fluopicolide SC(concentration 75 g/667 m2),the second 50 % Frowncide SC(concentration 22.5 g/667 m2),the third 25 % Mandipropamid SC(concentration 30 g/667 m2),100 g/L Ranman SC(concentration 22.5 g/667 m2),and mixture of 70 % Propineb WP(concentration 150 g/667 m2) and 687.5 g/L Fluopicolide SC(concentration 75 g/667 m2).All of them had about 70 % control effects on potato late blight,and increased yield over 40 %and new value up to 400 RMB/667m2.68 % Metalaxyl-M WG showed to be unstable in the fields and the control effect only 33.26 %,adding yield 5.68 % and new value up to 68 RMB.At the same time,because of pathogen of potato late blight had the resistance to Metalaxyl-M,it did not apply in Sichuan.Fungicide interval on the controlling potato late blight was 7 days after the first spray and the optimal spray was 3 times.