Potential of three physically different formulations of biocontrol agent Thrichoderma harzianum199 was investigated in a field trial against wheat common bunt caused by Tilletia laevis Kühn. Wheat seeds of cv. Chamran were treated with liquid, semi-solid (gel mixed suspension) and solid (talc powder) formulations prior to planting. Field practices were performed based on Khuzestan wheat planting schedule and no chemical was used until harvesting. The results of analyzed data showed significant effect of formulation type on common bunt incidence. Tetraconazole (chemical check) showed common bunt reduction (97.7%) and among bio-formulations, gel-mixed suspension was significant in disease reduction (43.41%), but it was next to talc and liquid formulation in yield, harvested weight, healthy spikes and stem height. Talc formulation reduced bunt infection (39.07%) and showed better than gel mixed suspension in yield and some yield components. Conversely, liquid formulation enhanced bunt incidence (25.31%) but was almost same as the talc and better than gel formulation in yield and yield components. General findings of this experiment indicate that physical form of T. harzianum 199 formulation can effectively influence both common bunt prevention and agronomic potential of Chamran wheat cultivar.

Keywords: Biological control, biofungicide, formulation, Tilletia laevis, organic wheat

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