Crescimento micelial, produção e germinação de escleródios de Sclerotinia sclerotiorum na presença de fungicidas químicos e Trichoderma harzianum

Abstract

The chemical and biological control of Sclerotinia sclerotiorum are common measures for the management of white mold disease in different cultures, being able to reduce damages to yield and seed quality. In this work the objective was to evaluate the sensitivity of isolates of S. sclerotiorum to some chemical and biological products, commonly found in the market for seed treatment of plant species. The treatment design included the products: methyl thiophanate, fluazinam, pyraclostrobin, fluquinconazole, procymidone and Trichoderma harzianum in five concentrations (5, 10, 50, 100 and 500 ppm) and 4 replicates. Fungicides were mixed in PDA medium in the liquid phase, and poured to petri dishes, 20 ml of agar medium per dish. After solidification of the medium, 6 mm agar discs containing mycelium of the fungus were placed at the center of each dish and the mycelial growth was recorded daily to obtain the mean growth diameter, which was used to obtain the correlation curve between this variable and the products concentrations. The fungicide and antagonists were effective in reducing mycelial growth of both isolates, with variations among the isolates tested. In relation to the production of sclerotia, the greatest number of these propagules was observed in the control followed by pyraclostrobin and methyl thiophanate treatments and there was no unit formed in the substrate containing T. harzianum. All sclerotia produced in fungal colonies were able to germinate regardless the concentrations of the fungicides.