Efficacy of indigenous Trichoderma isolates against Pythium deliense Meurs, associated with soft rot of ginger

Yellowing and rotting of ginger rhizomes are a severe concern in many ginger-growing tracts of Kerala, where Pythium deliense Meurs has recently emerged as a pathogen from the rhizosphere of infected rotten rhizomes, which is proven to be pathogenic by Koch`s postulates. The present study evaluates the antagonistic potential of ten isolates of Trichoderma spp., isolated from the roots of healthy ginger, against P. deliense, causing soft rot of ginger by dual plate method. The efficacy of volatile and nonvolatile metabolite produced by the antagonistic Trichoderma spp. under in vitro conditions was evaluated against the pathogen. Among the ten isolates, eight isolates such as, ZGC T16, ZGC T17, ZGC T20, ZGC T23, ZGC T28, ZGC T30, ZGC T35, and ZGC T36 showed inhibition on mycelial growth, above 70% in a dual plate assay. The highest inhibition percentage was showed by ZGC T20 (99.19%) followed by ZGC T17 (87.00%), identified as Trichoderma ressei and Trichoderma virens respectively, under dual culture method and moderate inhibition due to volatile metabolites (3.5-39.55%). Nonvolatile metabolites produced by ZGC T20 (65.55%), ZGC T17 (53.95%), and ZGC T36 (53.82%) showed comparatively less efficiency. The potential ones (ZGC T20 & ZGC T17) were further evaluated under the pot culture study and in vivo greenhouse conditions. The study revealed that T. ressei and T. virens have high efficiency in preventing the soft rot of ginger caused by P. deliense.

Efficacy of indigenous Trichoderma isolates against Pythium deliense Meurs, associated with soft rot of ginger Keywords:

Biocontrol , Ginger , Pythium deliense , soft rot , Trichoderma