Suppression of Fusarium spp. in a maize and beans intercrop by soil fertility management

Abstract

Fusarium root rot of maize and beans is a common problem in Taita District, Kenya causing reduction in yields to the small scale farmers. The pathogen attacks maize and beans at all growth stages and causing rot at the seedling stage, yellowing of the leaves, stunted growth and death if severe. Potentially effective crop rotations to maintain the pathogen at low levels are not currently acceptable in this region due to the small size of farms and prices of fungicides which are out of reach to the small scale farmer. This study is aimed at assessing alternatives to the use of fungicides in controlling root infection by Fusarium spp in maize and beans. Field trials were done in Taita District where agriculture contributes to 95% of household income with very little or no fertility inputs in farms. The following were tested in the trial: three kinds of fertilizers, cow manure and Trichoderma seed coating. Planting was done during the long and short rains. Soil and roots were collected from the rhizosphere during harvesting and assessed for inoculum density, while the roots were evaluated for incidence of infection by Fusarium spp. The most common species in both soil and roots were Fusarium oxysporum (Schlecht) Snyd. et Hans. and Fusarium sporotrichoides Sherb. Addition of soil amendments had a positive effect of reducing root infection and in some cases lowering inoculum density in the soil. Of the four fertilizers tested, Mavuno had the highest yield and was the most effective in suppressing root colonisation by Fusarium spp.