Trichoderma harzianum as a biocontrol agent against Alternaria alternata on tobacco

Trichoderma fungi are the most popular agents used in a biological control. Therefore, our aim was to determine an impact of Trichoderma harzianum on the fungus Alternaria alternata - a causing agent of the brown spot disease on tobacco. In vitro analyses were made in several variants of double culture, in order to study the effect of diffusible and volatile metabolites. There was strong reducing effect on the development of A.alternata with various mechanisms of antagonistic influence. The volatile metabolites have also shown reducing effect. Some abnormalities were observed in the pathogen's morphology both in diffusible and volatile metabolites. The strong reducing effect of T. harzianum towards A. alternata can be applied in biological control of this pathogen.