Efficacy of a zero-residue strategy against field and postharvest diseases on strawberries.

In recent years, growing concerns associated to pesticide residues in fruit have led to develop alternative crop protection strategies, including zero-residue strategy (ZeR). We assessed the impact of a ZeR strategy on fruit quality and postharvest microbiota of strawberries (Fragaria x ananassa), compared to a conventional IPM strategy. Data on fungal pathogen incidence was gathered over two years in two Italian farms. Fruit picked from treated farms were sampled for yield, quality parameters and microbiota composition at harvest, after storage and at the end of shelf-life, while pesticide residues were quantified by accredited laboratories. Disease incidence showed no significant difference between the adopted strategies for either farm in both year. No systematic impact of the strategy was found on yield (commercial production, average fruit weight, number of fruit per plant), titratable acidity, total soluble solids. Minor differences were observed for fruit firmness and colour parameters. Quantification of residues on fruit returned lower levels for the ZeR strategy, although a long-term contamination by fosetyl-Al was noticed. Microbiota composition was unaffected by the crop protection strategy and resulted in very high levels of Botrytis at the end of shelf-life. The ZeR strategy showed comparable efficacy to the conventional strategy.