Preliminary findings on biocontrol of bacterial wilt and canker of tomato (Clavibacter michiganensis subsp. michiganensis) using Trichoderma harzianum after biofumigation

One of the most aggressive bacterial diseases in tomato crops is bacterial wilt and canker caused by Clavibacter michiganensis subsp. michiganensis (Cmm). Chemical control is questioned due to its negative effects on health and the environment. Within integrated disease management, one alternative is biocontrol with Trichoderma species. Another technique is biofumigation, which releases volatile compounds into the soil that inhibit soil-borne fungi and stimulate plant health. The aim of this study was to evaluate the potential of biofumigation and the use of Trichoderma harzianum for the control of bacterial wilt and tomato canker caused by Cmm in vitro and their effect on yields in a commercial tomato crop. The inhibition of phytopathogenic bacteria of the in vitro test and the number and weight of fruits per plant in a greenhouse were evaluated. The treatments were: tomato plants inoculated with Cmm with or without two strains of T. harzianum, alone and in combination with biofumigation. The in vitro test results showed, with both strains, no significant differences between the treatments, although the growth of Cmm was lower in the combination biofumigation and T. harzianum. One of the strains of T. harzianum (Th118) performed better than the other for yield (weight and number of fruits). However, the results do not show a synergistic effect between T. harzianum and biofumigation in the observed yield values.