In vitro and in planta assays for biological control of Fusarium root rot disease of vanilla

Abstract

Rhizosphere and phyllosphere organisms isolated from vanilla consisted of predominant colonizers such as Fusarium sp. (24 isolates) and Colletotrichum sp. (20 isolates). Other organisms were Rhizoctonia sp. (two isolates), Trichoderma spp. (seven isolates), Paecilomyces sp.( one isolate), Mucor sp. (three isolates), non-sporulating fungal species (10 isolates) and pseudomonas fluorescence (three isolates). When tested in vitro, six isolates showed more than 50% inhibition of Fusarium oxysporum f. sp. vanilla. These were two isolates of Trichoderma sp. (53.30-70.58), one isolate of Paecillomyces sp. (65.00%) and two isolates of P. fluorescens(59.15-32.50%) that were antagonistic to the pathogen. None of the non-pathogenic Fusarium species tested showed promising inhibitory effect on F. oxysporum f. sp. vanilla. The five promising isolates were tested in planta by challenge inoculation.Paecillomyces sp. provided 100 per cent protection study indicated the possibility of using paecillomyces sp. as a potential antagonist for F. oxysporum f.sp. vanilla.