Inhibitory effect of different plant extracts and antifungal metabolites of Trichoderma strains on the conidial germination and germ tube growth of Colletotrichum capsici causing chili anthracnose

Abstract Antifungal activities of twenty four plant extracts and secondary metabolites of five Trichoderma strains were tested against conidial germination and germ tube growth of Colletotrichum capsici. Hundred percent inhibition of conidial germination and shortest germ tube formation of Colletotrichum capsici were recorded in Azadiracta indica (leaf), Ocimum sanctum (leaf) and Curcuma longa (rhizome) extracts after 4 to 24 hours of incubation. Lantana camara (leaf) and Colocasia antiquorum (leaf) extracts exhibited less inhibitory against the pathogen. Different concentrations and different day-old metabolites of five Trichoderma strains were significantly affected to inhibit of conidial germination and germ tube growth of C. capsicci. The hundred percent inhibitions of conidial germination and shortest germ tube formation was exhibited at 2000 mg/l concentration of 30-day-old metabolites of T. harzianum IMI-392433 and the lowest inhibition of conidial germination and longest germ tube formation was recorded at 1000 mg/l concentrations of 10-day-old metabolites of T. pseudokoningii IMI-392431after 4 to 24 hours of incubation. This study showed that the plant extracts of Azadiracta indica (leaf), Ocimum sanctum (leaf) and Curcuma longa (leaf) posses high ability to inhibit conidial germination and germ tube formation of C. capsici and antifungal metabolites of T. harzianum IMI-392433 have good antagonistic activity on C. capsicci spore germination and germ tube formation and that can be used as potential biological control agent to control the Anthracnose disease of the pathogen.