Spatial distribution of roots, nematode populations and root necrosis in highland banana in Uganda

Abstract

Abstract Banana root distribution, nematodes, and necrosis were assessed in banana (Musa AAA) monoculture and banana-legume intercrops in Uganda, with the aim of establishing their relationship in order to enhance decision making with regard to management practices and sampling for nematode population and damage assessment. The intercrops had no effect on the vertical or the horizontal distribution of banana roots and nematodes. Approximately 90% of the root biomass was in the upper 0.3 m and none was below 0.7 m. Within 0.5 m of the banana mat, the majority of root mass was in the surface 0.15 m, but outside this radius more were found from 0.15-0.3 m. This spatial distribution suggests that fertiliser applications would be most effectively applied within a 0.5 m radius of the banana mat. Nematode species and root necrosis were uniformly distributed horizontally on the roots; vertical distribution differed among species. Significantly larger populations of Radopholus similis were found in the upper 0.3 m; none was present below 0.5 m. Helicotylenchus multicinctus and Pratylenchus goodeyi were found throughout the rooting profile; H. multicinctus density being high in the upper 0.5 m, while P.goodeyi was generally low throughout. More root necrosis was noted in the upper 0.3 m, coinciding with the greatest population density of R. similis and the greatest amount of root biomass. The spatial distribution of nematodes indicates that root sampling and nematicide application should be concentrated within 0.5 m of the banana mat.