Identification of aggressive species of Trichoderma from button mushroom farms (Agaricus bisporus) using morphological and molecular methods

Different species of Trichoderma especially T. harzianum (Th2 biotype in Europe and Th4 in America) considered as causal agent of green mould disease on button mushroom (Agaricus bisporus) casing beds. In this study، 100 fungal isolates were collected and purified from different mushroom growing units in Tehran province and Urmia (NW Iran). Totally، 60 isolates of T. harzianum، 27 isolates of T. virens، seven isolates of T. hamatum and six isolates of T. inhamatum were morphologically identified. The main infectious agent was T. harzianum. Specific primers were used for identification of different biotypes. Th2 and Th4 biotypes specific primers amplified 450bp fragment. Using these primers، 30 isolates of Th2 and Th4 biotypes called T. aggressivum f. aggressivum and T. aggressivum f. europeaum were identified from 60 isolates of T. harzianum. Colony growing rates of 60 fungal isolates were measured at 15، 20، 25، 30 and 35º C for determination of optimum growth temperature. These optimum temperatures for Tehran and Urmia isolates were 30º C and 22±2º C، respectively.