Evaluation of some Trichoderma isolates for biological control of potato wilt disease (Fusarium oxysporum) under laboratory and greenhouse conditions

Biological efficacy of Trichoderma species may differ due to variations in ecosystems. This study was conducted to assess the biocontrol efficacy of some native Trichoderma isolates against Fusarium oxysporum، an important causal agent of potato wilt disease under lab. and green house conditions in Shahrood Agricultural Research Center، Shahrood، Iran during 2006-2007. Fourteen isolates were collected among which eight showed promising ability in inhibiting the growth of the pathogen through dual culture and production of volatile and non-volatile inhibitors but T. asperellum (T2) and T. atroviride (T3) were almost more efficient than other isolates in inhibiting the mycelial growth of the pathogen in comparison to control (P ≤ 0. 01). Eight isolates were evaluated against the disease under green house condition. Potted plants treated with Trichoderma isolates + F. oxysporum showed lower disease incidence in comparison to Fusarium infested control (P ≤ 0. 05). Best disease control was observed in potted plants treated with F. oxysporum + T. asperellum (T2) showing 2. 5 % disease incidence in comparison to Fusarium infested control، in which disease incidence was 73 %.