Simple model for early prediction of flowering in apricot

High year-to-year apricot yield oscillations in Serbia are mostly caused by late spring frost. Thus, phenological prediction can help to get more stable apricot yields providing dates for timely frost protection. This study aimed to validate a feasible, easy to apply model for prediction of full flowering in apricot cultivars based on air temperature averaged over 30-, 45- and 60-day periods starting from January 1. The model, capable of predicting the onset of full flowering in apricot cultivars from a few weeks to up to two months ahead with acceptable accuracy, was originally developed using phenological data for 20 apricot cultivars grown in the Belgrade region and daily temperature records over the period 1995-2004. Reevaluation of the data set consisted of phenological records for 20 cultivars grown in the same region and temperature observations from 2009 to 2016. The mean absolute differences between the observations and predictions obtained by 30-, 45- and 60-day models were 5.5, 6.4 and 5.6 days, respectively, on average for all examined cultivars