ANTAGONISMO DE ISOLADOS DE Trichoderma spp. no BIOCONTROLE DE Rhizoctonia solani EM BATATA

Abstract

Potato cultivation is one of the most economically and nutritionally important crops in Brazil and worldwide, but its production is constantly threatened by soilborne diseases, especially rhizoctonia blight, caused by the phytopathogenic fungus Rhizoctonia solani. This pathogen is a necrophytic parasite with high saprophytic capacity, which makes management difficult through conventional methods such as the use of fungicides and crop rotation, as the fungus survives in the soil and in crop residues in the form of sclerotia. Trichoderma species stand out for their mechanisms of action against pathogens, the main ones being competition for nutrients and space, antibiosis (through the production of volatile and non-volatile metabolites), and mycoparasitism, where the hyphae of the antagonist coil around and degrade the cell wall of the pathogen. The aim of this study was to evaluate the potential of native Trichoderma spp. isolates (LAFIP) in controlling R. solani, using in vitro and in vivo tests. In the in vitro assays, in the pairing test, all isolates (LAFIO 001 to LAFIP 007) obtained scores between 1 and 2, while the control obtained a score of 5. The evaluation of Volatile Organic Compounds (VOCs) revealed the antibiosis mechanism, with the LAFIP 007 isolate demonstrating the greatest inhibition of mycelial growth of the pathogen, reaching 84.60% inhibition. Validation of the biological potential under in vivo conditions in potato tubers of the Ágata cultivar confirmed the efficacy of the isolates. Treatments with LAFIP 003, LAFIP 006, and LAFIP 007 resulted in 0% incidence of rhizoctonia in the tubers, a performance superior to the negative control (water) with 80% incidence and even to the commercial product (positive control) reference used with 2% incidence. These results demonstrate that the Trichoderma spp. isolates from the LAFIP collection possess high biological potential and represent a valuable and ecologically sound tool for the integrated management of rhizoctonia in potato cultivation in Brazil.