Organic Amendments and Soil Suppressiveness: Results with Vegetable and Ornamental Crops

Organic amendments are an important tool for the management of diseases of vegetable and ornamental crops. They include manure, crop and food residues, compost and organic fertilisers. Their use can help to control soilborne pathogens in vegetable and ornamental crops, especially when applied in conjunction with other management practices and considering a system approach. Composts and Brassica pellets are considered those more promising. The use of Brassica species as green manure is considered a type of biofumigation that involves the release of volatile and toxic compounds. Compost involves different modes of actions, mainly correlated to its microbial community and the presence of biological control agents. Organic amendments can be successfully integrated with other control strategies, like soil solarisation and grafting on resistant rootstocks, to control soilborne pathogens affecting vegetable crops in field conditions. Another possibility is their application mixed in potting soils, which is of particular interest for ornamental crops.