Characterization of Trichoderma Isolates from Sugarcane Agro-Ecosystem and their Efficacy Against Colletotrichum falcatum Causing Red Rot of Sugarcane

A study was carried out with an aim to isolate and characterize Trichoderma isolates from sugarcane agro-ecosystem and to assess their potential to produce inhibitory secondary metabolites against Colletotrichum falcatum causing red rot of sugarcane. Ten isolates of Trichoderma were isolated from sugarcane rhizosphere soil samples, purified and characterized for their morphological characters and growth at different temperatures. Considerable variation was observed in growth rates and colony characters among the ten isolates. All isolates were screened in vitro for production of volatile and non-volatile metabolites inhibitory to C. falcatum using sealed Petri plate and culture filtrate screening methods, respectively. Non-volatile metabolites produced by Trichoderma were found more effective than volatile compounds in inhibiting C. falcatum growth with culture filtrates of eight out of the ten isolates exhibiting significant reduction in C. falcatum growth over control. Moreover, the level of inhibition accorded was higher by culture filtrates of the Trichoderma isolates as compared to volatile metabolites. Maximum inhibition of 51.5 % in colony area was recorded with culture filtrate of isolate STr-15 while in case of volatile metabolites highest inhibition observed was only 14.7 % (isolate STr-23). The study indicates that non-volatile metabolites produced by Trichoderma sp. have the potential to effectively inhibit C. falcatum and need to be explored further for red rot management.