Extract of winter cover plantsagainst soil phytopathogens

Abstract

Annual crops are generally affected by diseases caused by soil phytopathogens, which impair agricultural production and generate economic losses. Among the most common phytopathogens are Sclerotinia sclerotiorum, Fusarium sp. and Macrophomina phaseolina. Although the beneficial effect of green manure species in crop rotation is already known in terms of protection and soil fertility, 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 plant extract on soil phytopathogens. A 5% aqueous extract of black oat (Avena strigosa), hairy vetch (Vicia villosa) and radish (Raphanus sativus) was evaluated on Macrophomina phaseolina, Fusarium sp. and Sclerotinia sclerotiorum. Mycelial growth experiments were carried out in PDA cultivation. For S. sclerotiroum, the production of sclerotia was also evaluated. In another bioassay, the emergence of soybean seedlings and the incidence of phytopathogens in the substrate with the addition of cover plant extracts were evaluated. There was a difference between treatments for the fungus M. phaseolina, with emphasis on the reduction in mycelial growth of 26.3% by treatment with radish aerial part in relation to the control. There was no inhibitory activity on Fusarium and S. sclerotiorum fungi, although there was a difference in activity between shoots and roots of plants. Extracts from all plants, both shoots and roots, individually or in mixture, inhibited the formation of S. sclerotiorum sclerotia. Turnip and oat extracts also inhibited the incidence of Fusarium in soybean seedlings. The results obtained demonstrate the effect of cover crops on soil phytopathogens.