Abstract

HOYOS-CARVAJAL, Liliana et al. Evaluation of Trichoderma spp. isolates against Rhizoctonia solani and Sclerotium rolfsii under in vitro and greenhouse conditions. Agron. colomb. [online]. 2008, vol.26, n.3, pp.451-458. ISSN 0120-9965.

The biological effectiveness of eight isolates of Trichoderma spp. coming from Colombian soils was evaluated under in vitro and greenhouse conditions for the controlled causal agents of damping-off, Sclerotium rolfsii and Rhizoctonia solani. In vitro analysis showed the antagonistic capacity of all evaluated isolates. Under greenhouse conditions, four isolates were highly effective against S. rolfsii in bean nursery plants (>90% of disease reduction) and two isolates were effective against R. solani in cotton nursery plants (58 and 61% of disease reduction). The analysis UP-PCR and DS-PCR permitted the determination of three groups of isolates. Within these associations no clear link between the position in the dendrogram and antagonistic activity was found, but it allowed separation of species of Trichoderma by groups and even within isolates of the same species. The results indicate that the mycoparasitic capacity of Trichoderma spp. varies according to the phytopathogen fungi, showing a broad specificity of the antagonist for its substrate that is attacked by the fungus. Therefore it is necessary to make careful selections of the isolates of Trichoderma to be used in pathogens control programs.

Keywords : biological effectiveness; biological control; phytopathogen fungi; UP-PCR; DS-PCR.

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