Resumo
The biological control of Rhizoctonia solani by the use of Trichoderma harzianum and Pseudomonas fluoresce was studied in laboratory and greenhouse conditions. Tomato seeds (Lycopersicon esculentum L., cv. AGROCICA 33), were inoculated by dipping them in an inoculum suspension of isolates of Pseudomonas spp. (1x108 ufc/mlj and Trichoderma spp. (2 x 106 spores/ml). These seeds were sown unsterilized soil previously (72 h) inoculated with an isolate of R. solani RS-25. The pathogen inoculum, R. solani RS-25 growth obtained in sunflower seeds was utilized. During 30 days from sowing, seedling emergence and development, dumping-off incidence and R. solani pathogenicity degree were evaluated. At 10 days, the emergence rate in the control treatment was of 58,44%, while the treatment with the antagonistic organisms increased seedling emergence, as well as decreased to the damping-off incidence in 12.15% to 68,81% as compared to the inoculated check.
Três isolados de Pseudomonas spp. fluorescentes e dois de Trichoderma spp. foram selecionados in vitro pelo seu potencial de biocontrole de Rhizoctonia solani. Semente de tomateiro Lycopersicon esculentum L., cv. AGROCICA 33, tratadas por imersão nas suspensões dessas bactérias (1 x lO8ufc/ml) e fungos (2 x 106 esporos/ml), quando semeadas em solo não esterilizado, previamente infestado com R. solani, mostraram aumento significativo na emergência e peso das plantas e diminuição significativa em damping-off. Entretanto nenhum agente biocontrolador foi superior ao tratamento químico em todos os parâmetros avaliados.
Resumo
The biological control of Rhizoctonia solani by the use of Trichoderma harzianum and Pseudomonas fluoresce was studied in laboratory and greenhouse conditions. Tomato seeds (Lycopersicon esculentum L., cv. AGROCICA 33), were inoculated by dipping them in an inoculum suspension of isolates of Pseudomonas spp. (1x108 ufc/mlj and Trichoderma spp. (2 x 106 spores/ml). These seeds were sown unsterilized soil previously (72 h) inoculated with an isolate of R. solani RS-25. The pathogen inoculum, R. solani RS-25 growth obtained in sunflower seeds was utilized. During 30 days from sowing, seedling emergence and development, dumping-off incidence and R. solani pathogenicity degree were evaluated. At 10 days, the emergence rate in the control treatment was of 58,44%, while the treatment with the antagonistic organisms increased seedling emergence, as well as decreased to the damping-off incidence in 12.15% to 68,81% as compared to the inoculated check.
Três isolados de Pseudomonas spp. fluorescentes e dois de Trichoderma spp. foram selecionados in vitro pelo seu potencial de biocontrole de Rhizoctonia solani. Semente de tomateiro Lycopersicon esculentum L., cv. AGROCICA 33, tratadas por imersão nas suspensões dessas bactérias (1 x lO8ufc/ml) e fungos (2 x 106 esporos/ml), quando semeadas em solo não esterilizado, previamente infestado com R. solani, mostraram aumento significativo na emergência e peso das plantas e diminuição significativa em damping-off. Entretanto nenhum agente biocontrolador foi superior ao tratamento químico em todos os parâmetros avaliados.