EVALUATION OF BIOACTIVITY OF NEEM FORMULATIONS AGAINST THE MAJOR PESTS OF COTTON

摘要

Ovicidal action of neem azal - F on the eggs of Helicoverpa armigera revealed that the egg hatchability was minimum (1 3.3%) in neem azal - F1 % at 5 ml / lit followed by 16.7 % in neem azal - F 5% at 1 ml/lit. Feeding inhibition study revealed that the area fed by Spodoptera Htura was minimum in neem azal-F5% at 1 ml/lit (0.84cm~2) followed by 1.41 cm~2 in neem azal-F1 % at 5 ml/lit. Regarding the bioefficacy of neem azal - F, all the treatments were superior over untreated control in reducing the pest incidence of leafhoppers, white flies and H.armigera larvae and their damage. With reference to yield maximum yield (2294 kg/ha) was recorded in neem azal - F1 % @ 5 ml/it and pesticide alternated followed by neem azal -F 1%@5ml/lit (2268 kg/ha). Neem azal - F 5% + pesticide alternatively, recorded the highest cost: benefit ratio of 1:6.4 and 1:6.6, in the first and second field trials, respectively. From all the four trials with the two cultivars namely MCU 5 and RCH 2, neem azal - F 5% @ 0.5 ml/lit + pesticide alternatively, neem azal - F 5 % @ 1.0 ml/lit and neem azal - F 1 % at 5 ml/lit were adjudged as the best treatments in the management of major pests of cotton.