Tratamento de sementes de ervilha para o controle de Ascochyta pisi em sistemas de produção orgânica

Abstract

Pea (Pisum sativum L.) which has a wide variety of uses, due to the high nutritional value, can be used for animal feeding as well as food source for humans. Ascochyta blight disease is one of the most devastating diseases of this leguminous crop and is favored by cool climate associated with high relative humidity. The pathogen can be transmitted by infected seeds. With the increasing demand for healthier products without the use of chemical, the organic system of production is in expansion. The effectiveness of seed treatments, accepted by organic regulations, against A. pisi was evaluated. The treatments consisted of commercial biofungicides, experimental formulations based on microorganisms cultivated in laboratory and vegetal extracts, resistance inducers, physical methods based in the thermotherapy (aerated steam and hot water), and low energy electrons and the association of the physical methods and biological agents had in five experiments. Pea seeds, naturally infected with A. pisi were sown in sterilized commercial organic substrate and maintained under greenhouse conditions. Plant emergence and infection index were evaluated two weeks after sowing. Extract of Thymus vulgaris, Clonostachys rosea IK 726, the commercial product Micosat (Glomus sp. + Pseudomonas fluorescens + P. borealis + Bacillus subtilis), and the association of physical method with low energy electrons 140 and 130 kV with biological agent Bacillus subtilis (Serenade) were as effective in suppressing A. pisi as the standard chemicals used as controls.