Sensibilidad in vitro de especies de Trichoderma spp. aisladas de suelos forestales a fungicidas de diferente modo de acción.

Abstract

The aim of this study was to analyze the sensitivity of two species of Trichoderma spp. fungi (T. harzianum and T. longibrachiatum) isolated from forest soils to different modes of action. The active ingredients were: thiabendazole, tebuconazole, azoxystrobin, fludioxonil, and the doses were: 0;0.1;1;10;100 mg/L. The experiments were carried out using a completely randomized design with four replicates, each replicate consisting of a Petri dish. Box-and-whisker plots were used for the analyses and arithmetic mean differences were established using 95% confidence intervals. From the 10-day cultures of the two fungi, mycelial discs of 5 mm diameter were taken and placed in PDA mediumwith their respective fungicide, the Petri boxes were incubated at a temperature of 24±2°C under dark conditions. The mycelial diameter was evaluated in two directions (vertical and horizontal). The estimation of lethal concentration (CL50) was performed to determine the variability between isolates of a population to measure its fungitoxic potency. The results obtained show that T. longibrachiatum have greater tolerance to the fungicides Thiabendazole, Tebuconazole at doses of 0.1 and 1mg/L. T. harzianum and T. longibrachiatum in the presence of Azoxystrobin presented greater tolerance in the proposed doses of the present trial. T. harzianum presented greater tolerance to Fludioxonil in its totality, so its inhibition was 0%. To conclude, the Trichoderma harzianum and Trichoderma longibrachiatum amended with concentration of Thiabendazole and Tebuconazole resulted to be of high fungitoxicity on the contrary the concentrations of Azoxystrobin and Fludioxonil resulted without fungitoxicity. Therefore, field compatibility studies of the two isolates with other active ingredients are recommended to counteract the negative environmental impacts caused by the exclusiveuse of agricultural pesticides.