No abstract

Wild plant fruit extract such as hinganbet, Balanites roxburghii, ritthaa/soap nut, Sapindus trifoliatus, shikekaaee, Acacia concinna, Neem, Azadirachta indica, Karanj, Pongamia pinnata and vekhand, Acorus calamus L. were evaluated to screen their efficiency for the control of sucking pests of Bt cotton during Kharif 2009 to 2012 at Cotton Improvement Project, Mahatma Phule Krishi Vidyapeeth, Rahuri. All the organic pesticide treatments were superior over untreated control. Among the evaluated organic pesticides the treatment with 5 per cent hingan bet extract @ 2 litre per hectare was observed to be effective in reducing pest population in which aphids, jassids, thrips and whiteflies of 22.68, 8.16, 14.53 and 10.97 per three leaves, respectively, were recorded with the seed cotton yield of 20.77 quintal per hectare. However, this treatment was statistically at par with 5 per cent ritthaa extract @ 2 litre per hectare. The treatment with 5 per cent ritthaa extract recorded aphids, jassids, thrips and whiteflies of 23.16, 9.87, 15.34 and 12.65 per three leaves, respectively, with the seed cotton yield of 20.09 quintal per hectare. The treatment with 5 per cent NSE @ 2 litre per hectare recorded 28.96, 12.61, 17.71 and 15.18 aphids, jassids, thrips and whiteflies per three leaves, respectively, with the seed cotton yield of 12.31 quintal per hectare. The phytotoxicity studies on leaf injury on tips and leaf surface, wilting, vein necrosis, epinasty and hyponasty showed that there was no phytotoxic effect of the evaluated pesticides on cotton crop at the evaluated doses. The counts on natural enemies in the treatments with hinganbet and ritthaa extract were more or less similar to those recorded in untreated control. This clearly indicated that there was no adverse effects on natural enemies due to spraying of hinganbet and ritthhaa extract at evaluated doses.

Entomopathogenic fungi Verticillium lecanii Zimmermen and Metarhizium anisopliae Metchnikoff have generated a great deal of interest in recent years because of their potential as bio-control component in integrated pest management of cotton. These two mycopathogens were evaluated against sucking pests of Bt cotton during Kharif 2011 and 2012 at Cotton Improvement Project, Mahatma Phule Krishi Vidyapeeth, Rahuri to find out the scope and potentiality of V.lecanii and M.anisopliae against sucking pests of Bt cotton in intra hirsutum Bt hybrid (RCH-2Bt). Mycopathogens V.lecanii (2 x 10 8 cfu/gm and 2 x 10 12 cfu/g) and M.anisopliae @ 2000 g/hectare were evaluated alone and in combination (V.lecanii + M.anisopliae). The observations were recorded on 3,5 and 10 days interval after each spray application. Pooled analysis of two years data revealed that V.lecanii (2 x 10 12 cfu/g) @ 2000 g/hectare + M.anisopliae (2 x 10 12 cfu/g) @ 2000 g/ha in combination was found more effective and significantly superior to its lower dose V.lecanii (2 x 10 8 cfu/g)@ 2000 g/ha + M.anisopliae (2 x 10 8 cfu/g) @ 2000 g/ha. It was proved superior over all other treatments in reducing aphids, jassids, thrips and whitefly population, however, it was at par with V.lecanii (2 x 10 12 cfu/g) @ 2000 g/ha. Thus, V.lecanii (2 x 10 12 cfu/g) @ 2000 g/ha was found to be the effective dose against all major sucking pests of cotton. Investigation on evaluation of entomopathogenic fungi against natural enemies of sucking pests in Bt cotton revealed that there was no significant adverse impact of V. lecanii and M. anisopliae on the activity of natural enemies viz., Chrysoperla and Coccinellids; when compared with the population of natural enemies in control. Sole and combine application of V. lecanii and M.anisopliae at all the evaluated doses were not found toxic to natural enemies.