Isolation and screening of Trichoderma strains antagonistic to Sclerotinia sclerotiorum and Sclerotinia minor

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.