PT - JOURNAL ARTICLE AU - Luis Hugo Moreno Luna AU - Andrew G. Reynolds AU - Frederick Di Profio TI - Crop Level and Harvest Date Impact Composition of Four Ontario Winegrape Cultivars. I. Yield, Fruit, and Wine Composition AID - 10.5344/ajev.2017.17019 DP - 2017 Oct 01 TA - American Journal of Enology and Viticulture PG - 431--446 VI - 68 IP - 4 4099 - http://www.ajevonline.org/content/68/4/431.short 4100 - http://www.ajevonline.org/content/68/4/431.full SO - Am J Enol Vitic.2017 Oct 01; 68 AB - Pinot gris, Riesling, Cabernet franc, and Cabernet Sauvignon vines from a single vineyard in Virgil, Ontario were subjected to two crop levels, full crop (FC) and half crop (HC), in which crop was reduced in HC to one basal cluster per shoot at veraison. Crop level treatments were combined with three harvest dates: T0 (commercial harvest), T1 (three weeks after T0), and T2 (six weeks after T0), all with subsequent wine production. Berries, must, and wine were analyzed. Reductions in crop led to an increase in Brix, reduced yield, and cluster number in all cultivars, and increased cluster weight in Cabernet franc. Delayed harvest date also increased Brix and pH and reduced titratable acidity (TA) and berry weight. Effect of harvest date in berries carried over to musts and wines: increased pH and TA in T2 treatments was associated with reduced anthocyanins, phenols, and color intensity in red cultivars. Delayed harvest date had a greater magnitude of effect than crop reduction; thus, maintaining a full crop with a later harvest date might have a greater beneficial impact on potential wine quality than reducing crop level.