Influence of Two Cover Crops (Arachis repens L. and Desmodium adscendens Sw.) on Root Infestation of the “Great Dwarf” Dessert Banana Cultivar (Musa sp.) by Plant-parasitic Nematodes in Southeast Côte d’Ivoire

Abstract

Context: In Côte d’Ivoire, industrial banana plantations are faced with the problem of weediness. However, the use of herbicides as a means of control presents significant risks for human health and the environment. The abandonment of these products for more ecological alternatives such as cover crops is imminent. Aims: This study aimed to compare the relative abundance and the density of the main plant-parasitic nematodes in the roots of banana and cover crops according to three weed management treatments. Study Design and Methodology: The experimental design was a three-repeat Fisher block of three treatments consisting of implementation of A. repens and D. adscendens as cover crops and spraying of two synthetic herbicides (glufosinate and glyphosate) for weed management. The relative abundance and density of nematodes in the roots of banana and cover crops were assessed quarterly after extraction by the rapid double centrifugation-flotation method and enumeration under an optical microscope. Results: Both cover crops and banana plants had their roots infested by the major parasitic nematodes evaluated (Radopholus similis, Pratylenchus spp., Helicotylenchus spp., Meloidogyne spp., Rotylenchulus reniformis and Hoplolaimus pararobustus). These infestations were not a function of weed management treatments. Compared to the use of herbicides, A. repens and D. adscendens used as ground cover did not significantly increase or decrease nematode dynamics in the plots. Individuals extracted from the roots of the cover crops, and particularly from D. adscendens, were more numerous than from the roots of the banana plants. In terms of proportions, Pratylenchus spp., R. similis, Helicotylenchus spp. and Meloidogyne spp. were most abundant. R. reniformis and H. pararobustus as well as various nematodes (plant parasites: Hirschmanniella spp., Xiphinema spp., ..., and non-plant parasites: fungivorous, carnivorous, bacterivorous, ...) were in the minority. Conclusion: The results, particularly those of A. repens, could be useful in the biological, ecological and sustainable management of weed in banana plantations without important risks of pest pressure.