Management of root-knot nematodes (meloidogyne spp) tnokra (abelmoschus esculentus (l) moench) using nematode suppressive crops and organic soil amendments
This study was undertaken to develop an intergraded root- knot nematode management strategy in okra by using crop rotation of nematode suppressive crops and incorporation of organic amendment in to the soil. Several cereals and legume crops were screened in a greenhouse and okra was used as a control. The greenhouse experiment revealed that maize, sorghum, millet and guwar were suppressive to root-knot nematode. Pigeon pea was moderately susceptible while cowpeas and green grams were susceptible. Aller the greenhouse experiment, three IIJUl/.e varieties (bubycoru. swectcornund pioneer- Ph3253) and guwar were selected for a repeat experiment under field conditions in rotation with okra. Results showed that guwar and swcctcorn were the 1110stsupprcssi vc followed by maize cv Pioneer (Ph3253) and Babycorn. Based on the results of greenhouse experiments, four crops namely guwar, sweet com, baby com and maize cv Pioneer (Ph3253) were selected for their effectiveness in suppressing rootknot nematodes in rotations with okra. The findings from this study demonstrate that one season rotation of these suppressive crops with okra was not enough to reduce nematodes to levels below economic damage threshold because nematode populations quickly build up when okra was planted immediately after these crops. Rotation of sweetcom followed by okra appeared to be more effective in reducing nematodes build up as it recorded least population build up followed by guwar, maize cv Pioneer (3253) and Baby corn in that order. Farmyard manure was incorporated into the soil before planting okra after these selected crops to determine the effect of combining rotation- of suppressive crops and organic amendment in root- knot nematode management. There was clear evidence that combining organic amendment and crop rotation incorporating nematodes suppressive crops was more effective in reducing nematode population in the soil than rotation alone. Reduction of the Meloidogyne population in the soil was higher in soils where guwar was planted followed by okra indicating that this is a good combination in rootknot nematode management. Among the rotation cycles tested was sweet corn in the first season followed by okra in the next season. This study shows that integrated management approach in root knot nematodes management is the way forward because it is more effective and sustainable in the long run. Organic manure (farmyard manure) incorporated in guwar and rotated with sweet corn can be recommended to farmers as rotation crops because of their performance in this study. Also because they mature fast and have ready market. Once adopted, this integrated approach will result ill increased yields and income to smallholder farmers. It is affordable, easy to apply as well as environment friendly and hence sustainable over a long period of time. Farmers will reap multiple benefits.