Characterization of chilli root knot nematodes (Meloidogyne spp.) and evaluation of sodom apple (Solanum incanum l.) plant extract and Trichoderma viride c. as control agents in Nakuru County, Kenya

Abstract

Chilli (Capsicum annum L.) is a tropical and sub-tropical crop grown for its pungent tasting fruits and sour leaves. Chillis are prone to root knot nematodes (Meloidogyne spp.) which reduce their quality and yields. The study focused on characterisation of root knot nematodes infesting chilli in Nakuru County, investigation on the use of sodom apple fruit extracts in controlling root knot nematodes, the use of Trichoderma viride as a potential bio-control agent against root knot nematodes and evaluation of the effect of root knot nematodes on the uptake of nitrogen and phosphorous in chilli when sodom apple fruit and Trichoderma viride extracts were applied. Infested root samples were drawn randomly from 7 sub-counties of Nakuru County. Three farms were sampled per sub-county. One of the farms had heavy infestation by root knot nematodes. The root samples were analysed at Egerton University Department of Biological Sciences laboratory. Perineal patterns cut on the nematodes indicated that the root knot nematode present was Meloidogyne hapla. The efficacy of sodom apple fruit extracts against the root knot nematodes was tested under greenhouse and field conditions. 300 grams of sodom apple fruits (Solanum incanum) were blended and dissolved in 1 liter of water. Four dilutions were obtained through serial dilution (100%, 50%, 25% and 12.5%). The extracts were applied on chilli plants that were pre-infected with Meloidogyne spp. at the rhizosphere. Evaluation with sodom apple fruit extracts after treatment of plants showed that there was significant effect on plant heights, number of galls, stem diameter and leaf number in chilli. Highest heights were recorded in the 50% treatment of the field experiment. The lowest number of galls in the field experiment was in the 25 % treatment. Evaluation after treatment of plants with different concentrations of T. viride isolates showed that there was no significant effect on plant heights, number of galls, stem diameter or leaf number in chilli. The nitrogen and phosphorous levels indicated there was significant difference in the nutrient levels when different treatments of Trichoderma viride and sodom apple fruits were applied on chilli with root knot nematodes. All treatment effects were determined by one way ANOVA using SAS program (Version 9.3). The characterization of the nematodes has provided information that will aid in proper control of nematodes affecting chilli leading to improved livelihoods. Since the sodom apple fruit extracts were found to be effective in managing the root knot nematodes, they can be recommended to farmers as part of the integrated management system of pests in chilli by formulation of nematicides.