Screening of Trichoderma isolates as biocontrol agents against banana wilt pathogen and evaluating organic biomass wastes for mass production of conidia

Abstract

Fusarium wilt disease of banana is a serious threat in the banana growing areas in the world including Sri Lanka and no effective fungicide or resistant cultivars are available to date. Nevertheless, fungicides are extensively being used. Biological control is one of the environmentally sound alternatives in such instances. Therefore, the main objectives of the study were to screen potential Trichoderma isolates as bio control candidates and to evaluate cheap, simple and abundant substrates for the mass production of Trichodermafor practical application. Trichoderma spp. isolated from rhizosphere of banana (cv. Kolikuttu) from different areas of commercial banana fields in southern province of Sri Lanka were screened under in vitro conditionsfor their antagonistic potential against Fusariumoxysporumf. sp. cubense, the banana fusarium wilt pathogen. Trichoderma isolate T13 was the most effective in inhibiting the mycelial growth of Fusarium in Petri plate assay. Out of four different organic biomass wastes, (straw, banana leaf, banana pseudostem, and banana rind) that were tested for mass production of conidia of T13 in vitro, straw was found to be the best supportive organic material to enhance conidia production in broth cultures. Strain T13 was colonized in straw within 7 days and exhibited high spore density (3.167×1013conidia/mm3) and absorbance (λ550= 4.4890) with a strong positive correlation (r = 0.986). Those two parameters were significantly different (p < 0.001) compared to other treatments. Thus, the results revealed that the applicability of straw could be used as a congenial substrate for mass conidia production of Trichoderma isolate T13.