Efficacy of Fungicides and Bio-Agents Against Late Blight Severity, Infection Rate and Tuber Yield of Potato Shailbala , Pundhir V. S. Center of Advanced Studies in Plant Pathology, College of Apiculture, G.B.P.U.A &T. Pantnagar-263145 Abstract Late blight of potato appears regularly in epiphytotic proportion in all the hilly regions of the country and causes considerable reduction in yield and quality. Efficacy of eight fungicides and two bio-agents were studied against Phytopthora infestans, 8% N (2,6-dimethylphenyl) N-(methoxy acetyl) alanine methyl ester plus 64% mancozeb (Ridomil MZ-72) @ 0.2% was found effective to reduce the disease to lesser extent i.e. up to 95%. New fungicides 5-[4-(4-hydroxyphenoxy) phenyl-5-methyl-3-(phenylamino)-2,4-oxazolidine dione (KX-007), 5-methyl-5-(4 - phenoxyphenyl)-3-(phenylamino)-2,4-oxazolidinedione (JE-874), 2 cyano-N-[ethylamino carbony]-2 (methoxylmino) acetamide plus metalaxyl (Curzate) and Zinc propylene bis dithiocarbamate plus Iprovalicarb (Melody) were tested at different concentration. Among new fungicides, 2-cyano-N-[ethylamino carbony]-2-(methoxyimino) acetamide plus metalaxyl @ 0.3 was highly effective in reducing disease severity and protecting yield loss. AUDPC was found directly proportional to disease severity and inversely proportional to tuber yield. Maximum infection rate was recorded in control plot followed by Pant bio-control agent 1 and Pant bio-control agent 2 sprayed plot while minimum infection rate was recorded from 8% N-(2,6-dimethylphenyl)-N-(methoxy acetyl) alanine methyl ester plus 64% mancozeb sprayed plot. During 2003–04 and 2004–05 cropping seasons, 8% N-(2, 6-dimethylphenyl)-N-(methoxy acetyl) alanine methyl ester plus 64% mancozeb was the best treatment regarding tuber yield followed by Manganese ethylene bis dithio carbamate plus zinc (Mancozeb). Among new fungicides, 2-cyano-N-[ethylamino carbony]-2-(methoxyimino) acetamide plus metalaxyl @ 0.3% gave good yield. When treatments were compared for cost benefit ratio (C-B ratio), Manganese ethylene bis dithio carbamate plus zinc @ 0.2 % (2 sprays) proved best with highest C-B ratio. Top Keywords Potato, late blight, fungicides, bio-agent. Top |