Sclerotium rot, caused by Agroathelia rolfsii, is one of the main soil-borne diseases that limit tomato production. This study evaluates the efficacy of Amazonian Trichoderma species in controlling Sclerotium rot and stimulating plant development under field conditions in Manaus, Brazil. We used six Trichoderma isolates based on their previously evaluated performance under greenhouse conditions. The incidence of Sclerotium rot, tomato fruit production, and functional attributes of the isolates were evaluated. The isolates reduced the incidence of Sclerotium rot by up to 75 percentage points and also increased fruit production. T. rugulosum showed the best performance as it significantly reduced the incidence of Sclerotium rot and improved fruit yield. Although no differences were found in biomass allocation to plant organs, T. endophyticum, T. agriamazonicum, and T. asperelloides showed production of indolic compounds in vitro. The results highlight the potential of Amazonian Trichoderma isolates as biofungicides for use in sustainable tomato cultivation. In addition, we demonstrated the potential of Amazonian Trichoderma species both to reduce the incidence of Sclerotium rot and to increase fruit production. By reducing the use of synthetic agrochemicals, the use of Trichoderma promotes healthier and more sustainable agricultural practices.

Sclerotium rot, caused by Agroathelia rolfsii, is one of the main soilborne diseases that limit plant growth and tomato yield. This study evaluated the efficacy of Amazonian Trichoderma species to control sclerotium rot, and promote plant growth under field conditions, in Manaus, Brazil. We used six species (isolates) of Trichoderma based on their previously assessed performance in field trials. The incidence of sclerotium rot, tomato fruit yield and the production of indoleacetic acid (IAA) and siderophores were evaluated. The isolates reduced the incidence of sclerotium rot by up to 75% and also increased fruit yield. T. rugulosum had the best performance, as it greatly reduced sclerotium rot incidence and improved fruit yield. Although no differences were found in biomass allocation to plant organs, T. endophyticum, T. agriamazonicum, and T. asperelloides showed high production of IAA. The results highlight the potential of Amazonian Trichoderma isolates as bio fungicides to be used in sustainable cultivation of tomato. Furthermore, we show the potential of Amazonian species of Trichoderma to both reduce the incidence of sclerotium rot, and to increase the production of bioactive compounds that stimulate plant growth. By reducing the use of synthetic agrochemicals, the use of Trichoderma promotes healthier and more sustainable agricultural practices.