Cotton seed oil cake extract for the control of root-knot nematode, Meloidogyne incognita on soybean

Oilcakes available in sizeable amount, have certain physiologically active compounds which are used as nematicides and as manure. Under such a situation cotton seed oilseed has tremendous scope. It was extracted with water and methyl alcohol separately after 24 h incubation at 30°C and evaporating the solvents there after. Direct contact assay was carried out in vitro against root-knot nematode, Meloidogyne incognita larvae. One ml of double concentrations of 0.5, 0.25, 0.1, 0.05, 0.04, 0.03, 0.02 and 0.01 percent was put in 12 ml capacity glass vials over one ml of nematode suspension containing about 100 larvae, replicated thrice and stored at 30° ± 1°C for 24 and 48 hrs.

Results on mortality indicated an increase in percent kill with the increasing concentrations and exposure periods. Water extract was found to be more toxic than alcohol extract. At 0.05% conceptration, 100% mortality was obtained in water extract whereas only 17.0% mortality could be observed in alcohol extract after 24 hrs exposure. At even lowest concentraction (0.01%) the mortality was recorded to be 45.7 and 8.3% in water and alcohol extract respectively. When soybean roots were inoculated with treated larvae, marked dierences in penetration was observed. The 24 hrs water extract treatment of larvae was effective in inhibiting their mobility and infectivity. Thus, water extract could be used alone or as one of the components m the integrated nematode management programme.