Evaluation of selected soil fertility management interventions for suppression of fusarium spp. in a maize and beans intercrop

Abstract

Fusarium root rot of maize and beans is a common problem in Taita District, Kenya causing economic losses to the small scale farmers. The pathogen attacks maize and beans at all growth stages 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 practical due to the small size of farms while fungicides are out of reach to the small scale farmer due to high prices. This study aimed at assessing alternatives to fungicides in controlling root infection by Fusarium sp. in maize and beans cropping systems. Field trials were done in Taita District where agriculture contributes to 95% of household income with limited use of any soil fertility amelioration by farmers. The following were tested in the trials; three types of inorganic fertilizers, cow manure, and Trichoderma inoculant. 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 F. oxysporum (Schlecht) Snyd.et Hans. and F. sporotrichoides Sherb. Addition of soil amendments had a positive effect of reduced root infection and in some cases lowering inoculum density in the soil. Of the four integrated soil fertility interventions, Mavuno fertilizer had the highest yield and was the most effective in suppressing root colonisation by Fusarium spp