Native Trichoderma Isolates from Soil and Rootstock to Fusarium spp. Control and Growth Promotion of Humulus lupulus L. Plantlets

Fusarium genus is a wide host phytopathogen causing significant losses in multiple crops, including hops. There is limited information on the sustainable management of Fusarium spp. in hop fields. Trichoderma is an endophytic fungus used in agriculture as a biological control agent (BCA) and as a plant growth promoter. It has been used to antagonize Fusarium spp. in other crops. The objective of the current study was to identify indigenous hop field Trichoderma isolates with biocontrol and hop growth promotion capabilities. Three isolates of Fusarium and eleven autochthonous Trichoderma isolates collected from sustainable hop fields were evaluated in this work. Direct confrontation tests (the physical interaction between the pathogen and BCA and their competition for space and nutrient resources) and membrane tests (the capacity of the BCA to produce metabolites or enzymes through a cellophane film and inhibit the development of the pathogen) assessed the antagonism of these Trichoderma isolates against Fusarium culmorum, F. sambucinum, and F. oxysporum. A bioassay with hop plantlets inoculated with a spore suspension of Trichoderma was performed to assess its hop growth enhancement. T. hamatum (T311 and T324), T. virens T312, and T. gamsii T327 showed high growth inhibition of Fusarium spp. phytopathogens and high plant growth promotion. Native Trichoderma isolates from sustainable hop-producing soils have great potential as BCAs and hop growth promoters.