Amendment of Soil with Siam Weed and Sunn Hemp for Control of the Root-Lesion Nematode, Pratylenchus Brachyurus in Selected Cereals.

Field trials were conducted in 2013 and 2014 in the tropical rainforest zone of Nigeria to investigate the effects of siam weed and sunn hemp applied singly as organic amendments on population and damage of the root lesion nematode, Pratylenchus brachyurus, infecting maize and sorghum and to assess the effects of siam weed and sunn hemp on yield of root lesion nematode-infected maize and sorghum. The experimental field was naturally infested with Pratylenchus brachyurus.

                    Six week-old siam weed or sunn hemp seedlings were incorporated separately in maize or sorghum fields at the rates of 10 seedlings per plot (22,220 seedlings/ha) and 20 seedlings per plot (44,440 seedlings/ha). The experiment was rain-fed while manual weeding was carried out to keep the plots free of weeds.  At the ends of  the experiments, P. brachyurus population densities were significantly higher in control plots (P≤0.05) than in plots amended with siam weed or sunn hemp with correspondingly higher grain yield in the amended plots in both maize and sorghum plots in both years.  Twenty seedlings of siam weed or sunn hemp per plot incorporated into the soil in maize or sorghum plot significantly reduced the soil population of  P. brachyurus compared to ten seedlings per plot with correspondingly higher grain yield of maize or sorghum. The results of this study suggest that incorporating siam weed or sunn hemp in P. brachyurus-infected maize or sorghum field has potentials to suppress P. brachyurus population and increase the yield of associated cereal crops.