Leguminous crops as an alternative rotation with tobacco to control Meloidogyne javanica

Root-knot nematodes cause substantial economic yield loss in tobacco production and many other crops in the world. Their control has been achieved for decades by use of chemical nematicides. However, concern for the environment has led to the banning and phasing out of some effective chemical nematicides. The use of crop rotation is one of the environmentally friendly and sustainable management strategies for managing root-knot nematodes, insect pests and pathogens. The strategy is widely used by resource poor farmers in developing countries. In this study, greenhouse experiments were conducted with the objective of evaluating four leguminous crops (groundnut, sunhemp, common bean and cowpea cultivars) for their efficacy in the management of the root-knot nematode (Meloidogyne javanica). Experimental plants were grown in 15 cm diameter pots and artificially inoculated with nematode eggs. Four different initial inoculums levels of 0, 500, 1,000 and 1,500 nematodes eggs per plant were used. After inoculation the plants were maintained in the greenhouse for 54 days. Thereafter, the nematode reproductive factor and the number of eggs were evaluated. Significant differences (P<0.05) in nematode population built up were observed in plots with the different legumes. Generally, all the groundnut cultivars were effective in reducing populations while common bean was a susceptible host and supported high nematode populations. The results from this study demonstrate that some leguminous crops affect this pest’s capacity to develop within their roots. The test legumes may contain compounds that either kill or deter root-knot nematode reproduction. Key words: Antagonist plant, Meloidogyne javanica, crop rotation, groundnut, sunnhemp, common bean, cowpea.