Screening and test of non-polluted chemicals for controlling main tobacco fungal diseases in Guangdong

The tobacco black shank and brown spot have been become the important fungal diseases in Guangdong，so it is necessary to study the screening and application of non-polluted chemicals. In this paper， the research objects were tobacco black shank and brown spot. The results of laboratory bioassay indicated that the toxicities of dimethomorph and fluopicolide against Phytophtora parasitica var. nicotianae were the highest，and the values of median effective concentration（ EC50） were 0.56μg/mL and 0.25μg/mL respectively；the toxicity of Phenylamide was lower than that of dimethomorph and fluopicolide，and the EC50 was 1.14μg/mL. The toxicity of prochloraz amines against Alternaria alternata was the highest of all，and the EC50 was 0.26μg/mL；the toxicity of 75% trifloxystrobin·tebuconazole water dispersible granule（ WDG） was lower than that of prochloraz amines，and the EC50 was 2.66μg/mL. The results of flied experiments showed of. after a 15 d-treatment，the control effect of rotation application of 50% dimethomorph wettable powder（ WP） 1 500× and 80% Phenylamide WP 1 500 × against tobacco black shank was 87.23%；the control effect of rotation application of 45% prochloraz amines emulsion in water（ EW） 2 000× and 75% trifloxystrobin·tebuconazole WDG 2 500× against tobacco brown spot was 82.53%；the values of control effect of recommended agents were higher than that of contrast agents（ P < 0.05）. The research provided technical guidance for chemical control of tobacco fungal diseases，promoted the green safe production of tobacco，and ensured the yield and quality of tobacco.