Predicting the optimum harvest dates for apples using temperature and full-bloom records

SummaryThe relationship between the weather during the growing season and the UK Ministry’s recommended date for harvesting cv Cox’s Orange Pippin apples for long-term storage was investigated using data obtained between 1959 and 1980. No relationship could be found between meteorological data and the length of the growing season from the 50% full-bloom stage until the recommended harvesting date. However, good correlations were established between the number of days from 31 August to the recommended harvest date and meteorological variables which included temperature. July temperatures were particularly significant but the most significant were accumulated temperatures from June to September. Prediction of the Ministry’s recommended date was improved further by including the date of 50% full-bloom in a multiple regression which accounted for 72% of the variation. Using this regression the predicted and recommended dates differed by less than 3 days in all but one of the past 21 years. An equation was derived which enables the harvest date to be predicted on 1 September.