Screening of High Efficiency and Low Residue Fungicide of Tobacco Powdery Mildew in Field

PurposeTo study the control effect of chemical fungicides on tobacco powdery mildew and pesticide residues.

MethodsField efficacy trial was conducted to compare and analyze the effect of prevention and the effects on tobacco yield and quality about seven fungicides on tobacco powdery mildew, including 40% myclobutanil wettable powder (C1), 50% kresoxim-methyl water dispersible granule (C2), 10% difenoconazole water dispersible granule (C3), 30% triflumizole wettable powder (C4), 20% triadimefon EC (C5), 40% dimethachlone net wettable powder (C6) and 50% carbendazim wettable powder (C7). The pesticide residues of fungicides in flue-cured tobacco were analyzed and compared by gas chromatography-mass spectrometry.

ResultsC1, C2 and C3 had better control effects on tobacco powdery mildew than C7, among which, C2 had the best control effect (98.53%), and followed by C1 (88.99%). The results of tobacco leaf yield and quality measurement showed that the middle- and high-grade tobacco yield (845.48 kg/hm²) was the highest in the fields using C4 to control tobacco powdery mildew, accounting for 64.70% of the total harvested tobacco leaves; the output value reached 40212.64 yuan/hm², and the net income excluding pesticide costs was the highest (39573.64 yuan/hm²); pesticide residues in tobacco leaves were less, lower than the detection limit (0.05 mg/kg).

ConclusionC2 and C1 can be used as alternative pesticides for the control of tobacco powdery mildew, but the pesticide residue is slightly higher; and C4 has better control effect on tobacco powdery mildew, and the pesticide residue is lower.