BIOEFFICACY OF CONVENTIONALAND NEEMINSECTICIDES AGAINSTINSECTPESTS OF OKRA
R. PRASAD *
DEPARTMENT OF ENTOMOLOGY, BIRSA AGRICULTURAL UNIVERSITY, KANKE, RANCHI - 834006, INDIA
S.K. SATH *
DEPARTMENT OF ENTOMOLOGY, BIRSA AGRICULTURAL UNIVERSITY, KANKE, RANCHI - 834006, INDIA
D. PRASAD *
DEPARTMENT OF ENTOMOLOGY, BIRSA AGRICULTURAL UNIVERSITY, KANKE, RANCHI - 834006, INDIA
*Author to whom correspondence should be addressed.
Abstract
Experimental findings of the field experiments conducted during two consecutive seasons, springsummer and kharif of 1996 for the evaluation of bio-efficacy of five insecticides used in two different dosages against insect pests of okra viz. jassid (Amrasca bigutulla bigutulla Ishida) and fruit borer (Earias vittella Fab.) revealed that their effectiveness were found to be almost in order of oxydemeton methyl>chlorphriphos>quinalphos>neem oil > fenvalerate in reducing the incidence of both of the pest species. The insecticides hold also almost the same rank in terms of enhancement of yield of healthy and marketable fruits of okra and cost benefit ratio. As such, yield of marketable fruits viz. 90.2, 73.8 69.5, 76.1 and 67.7 q/ha and CBR of 1:16.4, 1:12.8, 1:10.6, 1:9.6 and 1:7.6 were obtained due to reduction in the incidence of jassids to the tune of 88.9, 80.9, 72.4, 72.3 and 59.9 per cent and that of fruit borer up to 90.8, 86.9, 72.4 and 67.7 per cent respectively over the unprotected crop by the foliar spray of the respective chemical insecticides (a) 500ga.i./ha, and neem oil (G) 3.5 per cent. The avoidable loss in yield was found up to 42.0 per cent as compared to the unprotected crop of okra.
Keywords: Okra pests, bioefficacy, management, insecticides, neempesticide