Substrates and cover crop residues on the suppression of sclerotia and carpogenic germination of Sclerotinia sclerotiorum

Abstract

Cover crops influence populations of microorganisms, such as a pathogen. In this work the objective was to evaluate the influence of different cover crops on the sclerotia of Sclerotinia sclerotiorum recovering rate in soil as well as the mycelial growth rate for recovered sclerotia. The influence of different substrates for carpogenic germination was also evaluated. The cover crops used in the experiment were Crotalaria juncea L., Urochloa ruziziensis R. Germ. & Evrard, Panicum maximum cv. Mombaça Jacq., Pennisetum glaucum (L.) R. Brown, Cajanus cajan (L.) Millsp.) and Stylosantes capitata Vog.; Stylosanthes macrocephala Ferr. Et Costa). The substrates used for carpogenic germination were agar-water, agar- water + filter paper, sand and mixed sand and soil. The cover crops showed efficiency in the suppression of S. sclerotiorum, especially for Stylosanthes spp. and Panicum maximum cv. Mombaça in the rate recovering of sclerotia and for Stylosanthes spp. in the rate of mycelial growth by providing a suitable environment for growth of antagonistic microorganisms. As for the number of carpogenic germinated sclerotia and for the number of apothecia formed on different substrates, the sand; agar-water and soil + sand mixture stood out, respectively.