Efeito do extrato de plantas de cobertura de inverno sobre fitopatógenos de solo

Abstract

Annual crops are usually affected by diseases caused by soil phytopathogens, which impair agricultural production generating economic losses. Among the most common phytopathogens are Macrophomina phaseolin, Fusarium sp. and sclerotinia sclerotiorum. Although the beneficial effect of green manure species in crop rotation is already known on soil protection and fertility, but information on species that provide better results in the management of certain soil phytopathogens is still limited. Thus, this work aimed to evaluate the effect of cover crops extract on soil phytopathogens. The work was carried out in the Phytopathology laboratory of the Federal University of Fronteira Sul in Laranjeiras do Sul-PR. The 5% aqueous extract of black oat (Avena strigosa ), hairy vetch ( Vicia villosa ) and forage radish ( Raphanus sativus ) on the Macrophomina fungi phaseolina , Fusarium sp. and Sclerotinia sclerotiorum . Mycelial growth experiments were carried out in PDA culture. For S. sclerotiroum , the production of sclerotia was also evaluated. In another evaluation, the emergence of soybean seedlings and the incidence of phytopathogens in the substrate were evaluated with the addition of cover crop extracts. There was a difference between treatments for the fungus M. phaseolina , with emphasis on the reduction in mycelial growth of 26.3% by the treatment with forage radish shoots in relation to the control. On the fungi Fusarium and S. sclerotiorum there was no inhibitory activity, although there was a difference in activity between shoots and plant roots. Extracts of all plants, both shoots and roots, individually or in mixture, promoted inhibition of sclerotia formation of S. sclerotiorum. Turnip and oat extract also inhibited the incidence of Fusarium in soybean seedlings. The results obtained demonstrate the effect of cover crops on soil phytopathogens.