Screening of Fungicides for the Control of Tobacco Brown Spot on Leaves at Different Maturity Levels
In order to investigate the resistance of different mature leaves to tobacco brown spot, and also the efficacy of fungicides to this dis-ease, the resistance of leaves with different maturities ( mature, proper and immature) to tobacco brown spot was measured, and proper tobac-co leaves and three kinds of maturity mixed tobacco leaves ( mature, proper and immature) were selected as the evaluation object of disease index, and the field efficacy of 15 kinds of fungicides ( 12. 5％ Myclobutanil ME, 325 g/L Difenoconazole · Azoxystrobin SC, 57. 60％ Cu ( OH)2 WDG, 40％ Dimethachlon WP, 8％ Validamycin SL, 80％ Bordeaux mixture WP, 50％ Kresoxim-methyl WDG, 10％ Difenoconazole WDG, 12％ Difenoconazole·Fluzoxamides SC, 25％ Azoxystrobin SC, 400 g/L Cloflurfenazole·Pyraclostrobin SC, 10％ Polyoxin WP, 38％ Pyraclostrobin·Boscalid WDG, 200 g/L Pydiflumetofen·Difenoconazole SC, 80％ Mancozeb WP)against tobacco brown spot were e-valuated by the increase of disease index. Results showed that highest resistance to brown spot was the immature leaves at upper position, fol-lowed by the proper mature leaves in the middle, and poorest resistance was the mature leaves at down position. Fifteen kinds of fungicides showed different field efficacy on tobacco brown spot. Results of the two investigation methods were relatively consistent in the field efficacy of 12 kinds of fungicides, such as 325 g/L Difenoconazole·Azoxystrobin SC, 57.60％ Cu( OH) 2 WDG. 325 g/L Difenoconazole·Azoxystrobin SC ( the field efficacies were 100％ and 85.64％ at 5 days after treatment, and 57.14％ and 64.92％ at 10 days after treatment) , 12％ Difeno-conazole·Fluzoxamides SC (82.81％ and 87.56％, 50％ and 70.82％), 25％ Azoxystrobin SC (100％ and 81.75％, 50％ and 53. 93％), 38％ Pyraclostrobin·Boscalid WDG (100％ and 89.18％, 77.78％ and 58％), 200 g/L Pydiflumetofen·Difenoconazole SC (86.74％ and 92.84％, 92.86％ and 81.79％) had better field efficacies. And 25％ Azoxystrobin SC (56.46％ and 54.95％) and 200 g/L Pydiflumetofen· Difenoconazole SC (60.90％ and 55.95％) still had good field efficacies after 15 days of application. Above all, the field efficacies of 325 g/L Difenoconazole·Azoxystrobin SC, 12％ Difenoconazole·Fluzoxamides SC, 25％ Azoxystrobin SC, 38％ Pyraclostrobin·Boscalid WDG and 200 g/L Pydiflumetofen·Difenoconazole SC against tobacco brown spot were much better, they could be used in the control of tobacco brown spot.
Tobacco brown spotField efficacyTobacco leaf maturityDisease resistance
万方数据
维普
