Low cost inputs for the management of sucking pests and bollworms in diploid cotton, Gossypium arboreum L.

摘要

The experiments were conducted to study the effect of seed treatment and release of Trichogramma chilonis (Ishii) on the incidence of sucking pests and bollworms in diploid cotton (Gossypium arboreum L.) at Agriculture Research Station, Hagari. The residual toxicity of imidacloprid treatment to seed was noticed upto 75, 60 and 45 days after sowing (DAS) by recording significantly less population of leaf hoppers, aphids and thrips, respectively. In contrast, efficacy was lost quickly to thrips followed by aphids, however plants were guarded from leaf hoppers for two and half months from sowing. Seed treatment failed to record any superiority with respect to whitely population due to its late appearance. Recommended insecticidal practice offered protection till 120 days from aphids and leaf hoppers and 45 days from thrips. Ovipositional activity of Helicoverpa armigera (Hubner) was uniform in parasitoid released and unreleased plots. Spraying of recommended insecticides and parasitoid release independently suppressed the larval population almost to same level. The reduction in the larval population was directly proportional to the density of parasitoid release. The parasitoid release @ 2.0 lakh/ha at 90 and 110 DAS was the best in recording lower damage to fruiting bodies (3.01 to 13.09%) followed by 1.50 lakh/ha dosage (3.39 to 15.36%) in G. arboreum cotton. Extent of egg mortality due to parasitoid activity was in proportion to dosage, density and frequency of parasitoid release. The RPP and parasitoid released treatment (@ 2.0 lakh/ha at 90 and 110 DAS) recorded higher number of good opened bolls (22 and 21.15/plant) and lower locule damage (12.48 and 17.28%). The RPP recorded higher seed cotton yield (7.20 q/ha) followed by seed treatment+T. chilonis @ 2.0 lakh/ha at 90 and 110 DAS (6.50 q/ha) in G. arboreum. The highest benefit cost ratio of 1.89 was reaped in parasitoid released treatment @ 2.0 lakh/ha at 90 and 110 DAS with imidacloprid seed treatment in G. arboreum.