Prediction of strawberry fruit yield

Data from commercial strawberry production in two districts of Norway were studied and compared with meteorological data. Reliable data for Trondelag (1973-2000) and Valldal (1975)-2000) were used. A strong correlation between yield level and fungicide used against Botrytis cinerea was found for Valldal, but not for Trondelag. For both districts yield was negatively correlated with temperatures in August previous to the fruiting year. In Valldal yield was positively correlated with temperature in April. Yield level was not significantly correlated with meteorological data during flowering and harvesting. Several regression equations for predicting yield were estimated; meteorological data, fungicides and year were used as variables. The cross-validation of the equations showed a good accuracy. The results indicated that climatic conditions during flower induction and flower differentiation were more important for yield than conditions during flowering and ripening. The regression method for predicting yield may be useful for the production and marketing of strawberries.