Integrated Management of Rotylenchulus reniformis and Concomitant Nematodes with Neem, Azadirachta indica and Nematicides in Cotton, Gossypium hirsutum

Trials under polyhouse and field microplot (4 m²) conditions were conducted to develop strategy for management of reniform nematode, Rotylenchulus reniformis in cotton. Population densities of the concomitant Tylenchorhynchus brevilineatus, Pratylenchus thornei and saprozoic nematodes, was also recorded. Under polyhouse condition the population density of R. reniformis increased from the initial of 250 to 600 per 200 cm³ soil in untreated control. The seed and/or soil treatments with neem seed kernel powder and nematicides, Carbosulfan, Cartap hydrochloride and Carbofuran significantly (P<0.05) reduced the nematode population density. Seed soaking with Triazophos @ 500 ppm for 6h followed by Cartap hydrochloride @ 0.2% a.i., and combination of seed treatment with Carbosulfan @ 3% a.i., + soil application of Carbofuran @ 0.5 kg ai/ha, resulted in maximum reduction in the population densities of all the three plant parasitic nematodes. Population density of saprozoic nematodes was also significantly (P<0.5) reduced due to all the treatments. In field microplots the population growth of R. reniformis was 17.6 times in untreated control but only 3.25–7.29 times in the different treatments. Seed treatment with Carbosulfan and Carbofuran alone and their combination caused maximum restriction (pf/pi=3.25) followed by Triazophos seed soaking (3.77) and seed dressing with NSKP @10% w/w (4.71–6.37), or Cartap hydrochloride @ 0.2% w/w (Pf/Pi =7.29). Yield/plot, bolls/plant, average plant height and average shoot weight were significantly (P<0.5) improved. Overall, Carbofuran @ 1 kg ai/ha was the best treatment which was followed by seed treatment with Carbosulfan 3% a.i. w/w + application of Carbofuran @ 0.5 kg/ha. Seed treatment with Carbosulfan @ 3% w/w, seed treatment with NSKP @ 10% w/w + application of Carbofuran 0.5 kg/ha, seed soaking with Triazophos 500 ppm for 6 h, seed treatment with Cartap hydrochloride @ 0.2% w/w and seed treatment with NSKP @ 10% w/w also reduced nematode population densities and nematode damage significantly (P<0.5). The rate of increase of T. brevilineatus and saprozoic nematodes was also decreased from 5.25 in control to 1.14–4.25 in the different treatments. The present findings suggest that seed treatment with any one of the Carbosulfan, NSKP, Cartap hydrochloride or seed soaking in Triazophos, in combination with half of recommended dose of Carbofuran (0.5 kg a.i./ha) could be used in management of reniform nematode in cotton.