Final Report to the NY Wine & Grape Foundation and Viticulture Consortium-East on research conducted by Dr. Lailiang Cheng and Dr. Terry Bates on the seasonal uptake and distribution patterns of nitrogen in Concord grapevines. This work provided a more thorough understanding on the dynamics of nitrogen use by grapevines, especially about the timing and importance of different sources of N for grapevine growth and development. This research has led to updated recommendations on the timing of application of N fertilizers and on the amount that is needed by most vineyards. This has led to a reduction of the amount of supplemental nitrogen fertilizer applied in many vineyards in New York, which has had a positive impact on grower profitability and environmental sustainability.

One of the components that influences yields in grapevines is the number of berries that set and mature on each cluster, or "fruit set". Each flower cluster contains many individual flowers, each of which has the potential to become a grape. However, not every flower will successfully pollinate or develop a healthy embryo and the surrounding tissue that becomes the fruit that we want.

This article covers some of the factors that influence fruit set in grapes and summarizes practices that growers could use to influence set. It was originally published in the June 2013 issue of the Finger Lakes Vineyard Notes.

Dr. Kees van Leeuwen is a professor of viticulture at the University of Bordeaux. His work focuses on the effects of environment on terroir. He is also the viticulture consultant for Chateau Cheval Blanc in St. Emilion, one of the premier producers in Bordeaux, which uses a high percentage of Cabernet Franc in its wines.