09-08-2013, 04:32 PM
Efficacy of various Trichoderma isolates against Fusarium oxysporum f. sp. cucumerinum causing wilt of cucumber
ABSTRACT
Trichoderma spp. has been extensively explored for the control of soil borne plant pathogens. Isolation of Trichoderma species, from seventeen soil samples and FYM, collected from different cucumber growing areas of Jammu and their identification based on morphological and cultural characteristics revealed the occurrence of four Trichoderma species and these were T. viride (10 isolates), T. aureoviride (3 isolates), T. harzianum (3 isolates) and T. atroviride (1 isolate).The toxic effect of diffusible metabolites released by the Trichoderma species on the test pathogen (F. oxysporum f. sp. cucumerinum) increased with the increase in the concentration of the culture filtrates. The diffusible metabolites released by T. viride (Tv2), T. aureoviride (Tau2) and T. viride (Tv8) isolate caused maximum inhibition of test pathogen while as T. viride (Tv7) isolate recorded least mycelial inhibition of the pathogen at all the concentrations tested. The vapour action of volatile compounds produced by different Trichoderma isolates significantly inhibited the growth of F. oxysporum f. sp. cucumerinum with varying degrees. Among the isolates, T. viride (Tv10), T. viride (Tv8) and T. aureoviride (Tau3) recorded maximum inhibition while as volatile metabolites released by T. harzianum (Th3) recorded minimum growth inhibition of the test pathogen. There was no correlation with the growth rate of Trichoderma species and production of metabolites.