Trichoderma based formulations control the wilt disease of chickpea (Cicer arietinum L.) caused by Fusarium oxysporum f. sp. ciceris, better when inoculated as consortia: findings from pot experiments under field conditions

Background Commercial/chemical pesticides are available to control Fusarium wilt of chickpea, but these antifungals have numerous environmental and human health hazards. Amongst various organic alternatives, use of antagonistic fungi like Trichoderma, is the most promising option. Although, Trichoderma spp. are known to control Fusarium wilt in chickpea but there are no reports that indicate the biocontrol efficacy of indigenous Trichoderma spp. against the local pathogen, in relation to environmental conditions. Methods In the present study, biological control activity of Trichoderma species formulations viz., Trichoderma asperellum, Trichoderma harzianum (strain 1), and Trichoderma harzianum (strain 2), either singly or in the form of consortia, was investigated against Fusarium oxysporum f. sp. ciceris, the cause of Fusarium wilt in chickpea, in multiyear pot trials under open field conditions. The antagonistic effect of Trichoderma spp. was first evaluated in in vitro dual culture experiments. Then the effects of Trichoderma as well as F. oxysporum, were investigated on the morphological parameters, disease incidence (DI), and disease severity (DS) of chickpea plants grown in pots. Results In dual culture experiments, all the Trichoderma species effectively reduced the mycelial growth of F. oxysporum. T. asperellum, T. harzianum (strain 1), and T. harzianum(strain 2) declined the mycelial growth of F. oxysporumby 37.6%, 40%, and 42%. In open field pot trials, the infestation of F. oxysporum in chickpea plants significantly reduced the morphological growth of chickpea. However, the application of T. asperellum, T. harzianum (strain 1), and T. harzianum (strain 2), either singly or in the form of consortia, significantly overcome the deleterious effects of the pathogen, thereby resulted in lower DI (22.2% and 11.1%) and DS (86% and 92%), and ultimately improved the shoot length, shoot fresh weight and shoot dry weight by 69% and 72%, 67% and 73%, 68% and 75%, during the years 1 and 2, respectively, in comparison with infested control. The present study concludes the usefulness and efficacy of Trichoderma species in controlling wilt disease of chickpea plants under variable weather conditions.