POTENCIAL DE CONTROLE BIOLÓGICO DE Rhizoctonia solani E PROMOÇÃO DE CRESCIMENTO EM PLÂNTULAS DE TOMATE INDUSTRIAL

Abstract

Industrial tomato production is highly susceptible to diseases, requiring rational disease management strategies such as the use of Efficient Microorganisms (EM). The aim of this study was to verify whether the application of EM can be used in the biocontrol of rhizoctonia leaf spot caused by Rhizoctonia solani in industrial tomato. Two tests were performed: in vitro and in vivo. The in vitro test evaluated the antagonism in four different strains of R. solani in PDA medium containing 5% EM. The in vivo test was conducted in a randomized complete block design (RBD), containing seven treatments with four replicates, five plants each. Treatments consisted in application of activated commercial product seven days before transplanting - DAT (T1); roots of seedlings immersed for five minutes in product (T2); application after transplanting, being one at the time (T3), after seven days (T4) and another after 14 days (T5); three applications (seven days before, at the time and 14 DAT) (T6) and control without product application (T7). R. solani isolate, strain NPF52, was inoculated in parboiled rice that, after being crushed, was incorporated into the soil. Following parameters were evaluated: stem diameter (DC), number of leaves (NF), fresh mass (MFPA) and dry mass of aerial part (MSPA), fresh mass (MFR) and dry mass of roots (MSR), as well as the intensity of disease (ID). Mycelial growth of the phytopathogen in PDA medium was reduced between 60.35% and 79.06%, in the four isolates, when the product was used at a concentration of 5%. Application of EM aided in the development of tomato plant expressed by morphometric parameters: stem diameter (T1, T3, T4, T5) and number of leaves (T3). Use of EM showed a positive effect when applied in a single dose at seven DAT (T4) and roots of the seedlings were immersed in the product for five minutes at the time of transplanting (T2). These treatments were able to reduce th intensity of rhizoctonia in industrial tomatoes grown in inoculated soil. Sequential applications of EM divided into three moments (before, transplanting day and after), at the manufacturer's dosage, showed no effect on control of R. solani in industrial tomatoes.