2018 ASHS Annual Conference

Assessing grape fruit maturity, potential wine quality at harvest, and the estimated optimal timing for harvest, can benefit both the grape grower and the winery to which the grapes may be sold. We have studied the timing of harvest over a period of 15 years for a large number of hybrid grape cultivars and correlated these times with growing degree days (GDD, base 50 Fahrenheit). These results will be reported for 16 cultivars for which GDD were recorded over a period of up to 15 years. The mean GDD will be reported, in addition to the range of extremes for earliest and latest harvest. For example, the mean GDD for 'Marquette' was 2757, with extremes of 2322 (an outlier?) and 2887. If the unusual extreme low is removed from the data set, the mean GDD is 2806 and nearly 80% of harvests fell between 2803 and 2887 GDD. Similarly, mean GDD for 'Frontenac' was 2878, with a range of 2676 to 3281, while for 'Vignoles', the mean was 3014, with a range of 2710 to 3374. Although harvest parameters (soluble solids, pH, TA) influenced harvest timing in several years, the data accumulated over 15 years have enabled a rough estimation of suggested harvest times for these and other hybrid grape cultivars grown in Nebraska vineyards.