THE INCIDENCE OF PLUTELLA XYLOSTELLA LINNAEUS IN CABBAGE –CROP- ECOSYSTEM OF MANIPUR VALLEY

Abstract

Replicated field trials were carried out at the College of Agriculture, CAU, Imphal during Rabi, 2009–2010 to study the comparative bio-efficacy of nine aqueous indigenous plant extracts and Nimbecidine against Diamond-back moth (DBM), Plutella xylostella Linnaeus in cabbage variety “Pride of India”. The results revealed that Nimbecidine @ 2000 ml ha-1 proved to be the most effective with three sprays mean larval population of 9.32 /plant as against 12.85 to 22.29 /plant in the cow-urine plant extracts and 39.20/ plant in untreated check. Melia azedarach and Jatropha gossypifolia extracts each @ 12,500ml ha-1 with their corresponding mean larval population of 12.85 and 16.42 /plant, respectively but dffered significantly from that of Nimbecidine. The extracts of Acorus calamus and Melothria perpusilla each applied @ 12500ml ha-1 having 22.29 and 21.04 larvae/plant, respectively also did not afford satisfactory control of the pest. However, all the insecticidal treatments were significantly superior to untreated check in minimizing the pest population. The highest mean yield (23.12 t ha-1) was obtained from Nimbecidine treated plots followed by the plots treated with M. azedarach (21.98 t ha-1), Artemisia nilagirica (21.25 t ha1), Andropogon nardus (20.22 t ha-1 ), J. gossypifolia (19.85 t ha-1) and Ageratum conyzoides (19.45 t ha-1) as against 17.39 to 18.30 t ha-1 in rest of the five insecticidal treatmented plots and 14.35 t ha-1 in untreated control.. The avoidable loss due to DBM infestation varied from nil in Nimbecidine sprayed @ 2000 ml ha-1 to 37.93 per cent in untreated check. Among the plots treated with insecticides maximum avoidable loss (24.78 per cent) was computed in the plots treated with A. calamus extract @ 12500 ml ha-1