Abstract

IBARRA-MEDINA, Verónica Azucena et al. Isolation and screening of Trichoderma strains antagonistic to Sclerotinia sclerotiorum and Sclerotinia minor. Rev. Mex. Mic [online]. 2010, vol.31, pp.53-63. ISSN 0187-3180.

Sclerotinia sclerotiorum (Ss) and Sclerotinia minor (Sm) drastically affect more than 400 plant species, and may cause crop yield reductions up to 50%. With the purpose to obtain potential microorganisms to control both pathogens, the isolation of Trichoderma strains from soil samples with different agricultural and forestry use was performed. Seventy-one fungal Trichoderma isolates (IBA) were obtained through sclerotia-trap techniques. Subsequently their mycoparasitic activities on mycelium as well as on sclerotia of both phytopathogens were assessed by in vitro dual cultures. The highest percentages of colonization (>90%) of the Trichoderma strains on Ss and Sm were found for the isolates IBA-3, IBA-4, IBA-38, IBA-54. The ability of Trichoderma strains to parasitize and to degrade sclerotia in general was aggressive for the strains IBA-3, IBA-4, IBA-23, IBA-38, IBA-46, IBA-54, and IBA-56. Based on morphological criteria, four of the most prominent strains were identified as T. viride (IBA-4), T. pseudokoningii (IBA-23), T. harzianum (IBA-38), and T. virens (IBA-46). These Trichoderma strains have important potential as antagonists to Ss and Sm.

Keywords : mycoparasitism; antibiosis; sclerotia degradation.