Fungi associated with Paspalum guenoarum seeds: their impact on physiology and control

Abstract

ABSTRACT: Of the natural pastures grown in southern Brazil, those of the genus Paspalum are the most important. One of the factors that hinder their cultivation is the availability of quality seeds, that are often compromised by the presence of fungi. This study determined the in vitro sensitivity of Paspalum guenoarum ecotype azulão seed-associated fungus to certain fungicides and to measure the efficiency of chemical treatments for fungal control and seed physiological performance. Bipolaris micropus, Epicoccum sorghinum, Curvularia geniculata and Fusarium incarnatum associated with seeds were tested in vitro against Carbendazim; Tiram, Fludioxonil; Metalaxil-M, Carboxina; Tiram and Tiofanato-metílico at 0, 1, 2.5, 5, 10 and 30 µg/mL. This experiment was conducted in a completely randomized design (factorial 4 × 4 × 6). Qualitative variables were compared using the Tukey test (P ≤ 0.05) and quantitative variables were subjected to regression analysis. Carbendazim; Tiram and Fludioxonil; Metalaxil-M had the best fungicidal performances, each inhibiting three of the four fungi with LD50s below 1 µg/mL. Subsequently, these two fungicides were used alone or in combination in the in vivo test. A completely randomized design was used and the means were compared using the Tukey test (P < 0.05). The chemical treatment of the seeds resulted in improvement of five of the six evaluated physiological parameters. The identification of the primary fungi associated with Paspalum seeds reported in this research, as well as damage done to them, can be diminished using appropriate measures such as seed treatments.