Infection Risk and Critical Period for the Postharvest Control of Gray Mold (Botrytis cinerea) on Blueberry in Chile.

Gray mold (Botrytis cinerea) is a major disease of blueberries (Vaccinium spp.), which require more than 15 days of shipment at 0°C to reach international markets. The aims of this study were (i) to determine the relative susceptibility of the flowering and fruiting stages, (ii) to determine the critical blueberry growth stages for postharvest gray mold control, and (iii) to determine the infection risks on the basis of weather conditions. The epiphytic colonization of B. cinerea of flowers and fruits was demonstrated in blueberry 'Brigitta' and 'Duke' in Antuco and Virquenco. In inoculated flowers and fruits in humid chambers at 20°C, full bloom and mature fruit stages were the most susceptible stages. Fungicide applications at the mature fruit stage appeared as the most critical period for gray mold control in stored fruits. The algorithm proposed, which was based on >6 h of wetness between 14 and 25°C, allowed the estimation of the periods of B. cinerea infection risk. A significant correlation between the B. cinerea infection risk and gray mold incidence in stored fruits was obtained (r = 0.96, P < 0.0001). Therefore, this algorithm has the potential to optimize fungicide applications under field conditions, but field validation of this algorithm remains to be determined.