Biocontrol evaluation of wheat take-all disease by Trichoderma screened isolates

Wheat take-all disease, caused by Gaeumannomyces graminis var tritici (Ggt), has been observed in different areas of Iran in recent years. Current biocontrol studies have confirmed the effectiveness of the Trichoderma species against many fungal phytopathogens. In this study, biocontrol effects of Trichoderma isolates were evaluated against take-all pathogen. Five (Trichoderma virens T65, Trichoderma virens T90, Trichoderma virens T96, Trichoderma virens T122 and Trichoderma koningii T77) isolates were selected after screening tests for antifungal effects against take-all pathogen and three (Trichoderma koningiopsis T149, Trichoderma brevicompactum T146 and Trichoderma viridecens T150) isolates were used as random selection. Also, Trichodermin B and Subtilin as commercial bioproducts were also used to evaluate biocontrol effects against take-all in greenhouse. In dual culture tests, five (T65, T90, T96, T122 and T77) isolates covered and colonized the colony of the pathogen. Microscopic studies revealed hyphal coiling (hyperparasitism) of isolates T65, T96 and T90 around Ggt hyphae. Culture filtrates and volatile metabolites of all isolates reduced the mycelial growth of take-all pathogen. T96, T65, mixture of eight isolates and Trichodermin B were more effective than other treatments to control the disease and reduced 25 to 55% disease severity and increased 27 to 59% dry weight of shoots and 23 to 58% dry weight of roots compared with control while disease reduction of seed coating method was more than soil treatment application. Although, based on shoots and roots dry weight, all of treatments showed significant differences with healthy plants.