BIOCONTROL OF Trichoderma spp. TO PATHOGENS OF SUGARCANE ROOT (Saccharum officinarum)

Wilting of sugarcane is produced by a complex of Fusarium species, such as F. andiyazi and F. sacchari, which induce rotting of roots. In order to control this disease and reduce the use of fungicides, biological control has been proposed by means of antagonists of the genus Trichoderma. The objective of this study was to evaluate in vitro and in sugar cane plants the antagonistic capacity of strains of Trichoderma against F. andiyazi and F. sacchari. The hypothesis was that at least one strain of Trichoderma inhibits the growth in vitro of Fusarium and favors the development of the sugarcane plants. Eighteen strains of Trichoderma were isolated and their percentage of inhibition was determined on the mycelial growth of Fusarium species with the technique of dual culture in potato dextrose agar culture medium. The experimental design was completely randomized, with four replicates per treatment. The degree of antagonism of Trichoderma was evaluated at 13 d. The strains T2 and T8 which showed the best characteristics of antagonism were selected for the in vivo bioassay. For the evaluation in vivo, the sterile substrate was inoculated with F. andiyazi and F. sacchari, and the roots of sugarcane plants with strains T2 and T8 of Trichoderma in a design of randomized blocks, with three blocks and three replicates for each treatment. The variables evaluated were plant height (cm), fresh and dry root biomass (g), number and diameter of stems (mm) and root length (cm). The strains T2 and T8 were determined with morphological and molecular identification as T. asperellum and T. koningiopsis. The effect of these species on the sugarcane plants was beneficial, given that they increased plant height, along with length, wet and dry biomass of roots.