EFFECT OF SOIL MANAGEMENT AND TRICHODERMA ASPERELLUM ON SEVERITY OF PASSIONFRUIT WILT DISEASE
Passionfruit is the third most important export fruit crop in Kenya after mango and avocado. Passionfruit wilt disease (PWD) is a major constraint because of its persistence in the soil and lack of appropriate chemical control resulting in high yield losses. The objectives of this study were to investigate effects of soil management and application of Trichoderma asperellum on control of PWD. Soils managed under organic, integrated and virgin systems, were collected from farmers fields and used to set up a bioassay in a greenhouse using the purple passionfruit. The soils were inoculated with T. asperellum at 5×107 CFU/ml and Fusarium oxysporum f. sp. passiflorae (FoP) four weeks later at 2.25×104 CFU/g. Disease severity was assessed by length of vascular discolouration and chlorosis. Microbial populations of the antagonists Trichoderma spp., fluorescent pseudomonads and actinomycetes were determined by serial dilution. Data were analysed using analysis of variance (ANOVA) and treatment means were separated using student-Newman-Kruels test. Disease severity was significantly lower (P≤0.05) in Trichoderma treated soils than non-treated soils with organic soils having the lowest severity. Organic soils had significantly higher (P≤0.05) population of the antagonists than virgin and integrated soils. Reduced disease severity in Trichoderma treated soils was as a result of microbial antagonism by T. asperellum against FoP. Organic matter improved efficacy of T. asperellum. The results propose an integrated and sustainable approach towards management of PWD by using biocontrol agent (T. asperellum) and organic matter.
Thuranira, M.D., Wasilwa, L.A. and Matiru, V.N. (2011). EFFECT OF SOIL MANAGEMENT AND TRICHODERMA ASPERELLUM ON SEVERITY OF PASSIONFRUIT WILT DISEASE. Acta Hortic. 911, 243-249
chlorosis, vascular discolouration, organic, integrated, virgin