Biocontrol of wheat Fusarium using Trichoderma strainsisolated from Algerian desert soils

Abstract: Root and crown rot of wheat caused by Fusarium species is a very common andeconomically important disease in many wheat-producing areas of the world, especially in aridregions. Fourteen strains of Trichoderma spp. were isolated from Algerian desert soils, usingthe soil dilution plate method, and assessed for their antagonistic activity against Fusariumcrown and root rot of wheat. Identity of Trichoderma spp. was confirmed by genetic analysisof ITS sequences. Trichoderma spp. efficiency was evaluated by in vitro and in vivo bioassaysagainst three species of the pathogen agent: F. culmorum, F. graminearum and F.verticillioides. In the in vitro bioassay (indirect confrontation), the highest percentages ofreduction in colony diameter were around 50% obtained with T. viride Tv.6. The seed treatmentby Trichoderma spp. isolates before sowing in a soil already infested by the pathogens, led toa significant decrease of disease severity compared to the control ones. The highest diseaseindex decrease (> 70%) was obtained with the two isolates of T. harzianum (Thr.4 and Thr.10)and T. viride Tv.6 against the three fungal pathogens.