Organic seed treatments of vegetables to prevent seedborne diseases

Seedborne pathogens of vegetables are responsible for the re-emergence of diseases of the past, as well as the introduction of diseases into new geographical areas. Seed treatment can be used to eradicate seedborne pathogens or to protect from soilborne pathogens. The European Commission Regulation (EC) No. 1452/2003 states that only organic seeds must be used in organic horticulture. Starting crop production with clean seeds is the background for a healthy crop. Physical seed treatments, including mechanical treatments, thermal treatments, radiations, and redox treatments can be highly effective. The use of natural compounds, which could be of organic or inorganic nature, is another useful tool. Organic compounds comprise plant extracts, essential oils, as well as purified microorganism compounds. Biological control, based on the use of antagonistic microorganisms, can be effective and sustainable to control seedborne diseases. Indigenous or introduced seed-associated microorganisms might suppress seed infections by pathogens. Numerous filamentous fungi, yeast, and bacteria have been studied as biological control agents against seedborne pathogens. Microbial interactions on the spermosphere should be deeply investigated in order to develop effective BCAs. Seed treatments with elicitors may be helpful to initiate a defence response already early in plant development and has the advantage of being applied in a contained environment. The main advantages and drawbacks for every type of seed treatment will be described, together with the mains knowledge and technology gaps concerning vegetable crops. The cost-effectiveness of the seed treatments will be considered. Integrated control strategies, including different seed treatments, could be helpful to guarantee a high level of disease control and production yield.