Effects of physical state of formulation on the potential of Trichoderma harzianum 199 against wheat common bunt

Potential of three physically different formulations of biocontrol agent Thrichoderma harzianum199 as a substitution for chemical seed treatment and a step toward organic wheat production was investigated in a field trial based on a randomized complete block design against wheat common bunt caused by Tilletia laevis Kühn. which imposes economic losses in some parts of the country and is a serious problem in organic wheat fields. 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 (p < 0.01) on common bunt incidence. Tetraconazole (chemical check) showed common bunt reduction (97.7%) and among bio-formulations, gel-mixed suspension was significant (p < 0.05) in disease reduction (43.41%), but 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 agronomical potential of Chamran wheat cultivar.