Preharvest treatments with alternatives to conventional fungicides to control postharvest decay of strawberry

摘要

Strawberry fruit are particularly perishable, and after the harvest they can suffer from desiccation, quality deterioration and mold. The main postharvest decay is gray mold, followed by Rhizopus rot, blue mold and Mucor rot, which are caused by Botrytis cinerea, Rhizopus stolonifer, Penicillium spp. and Mucor spp., respectively. The effectiveness of resistance inducers in the control of postharvest decay of strawberry was investigated in both postharvest and field trials. Commercial compounds basedon the biopolymer chitosan, benzothiadiazole, oligosaccharides, soybean lecithin, calcium plus organic acids, and fir and nettle extracts were tested in postharvest trials to assess their control of the decay of fruit in storage. With the same purpose, in field trials, the plants were sprayed five times with chitosan, laminarin, fir extract, and benzothiadiazole, and compared with a fungicide strategy based on cyprodinil plus fludioxonil and pyrimethanil. In the postharvest applications with 'Camarosa'strawberries, the highest disease reductions were obtained with the chitosan formulation, followed by benzothiadiazole, and calcium plus organic acids. In the preharvest trials, all of the treatments reduced postharvest decay of the strawberry cultivar 'Alba' fruit after one week storage at 0±1°C and exposure to 3 days shelf life. In the field trials, the effectiveness in reducing the disease of 1% chitosan was not significantly different from that of the fungicide-based strategy. Thus, with a view tothe protection of production without any negative effects on the fruit, our investigations show that application of resistance inducers could be a good alternative for integration with the use of chemical fungicides, or in organic agriculture, where theuse of chemical fungicides is not permitted.