Vine Size, Pruning Severity, and Vine Balance

How many fruiting buds should I retain on a Concord vine? A simple question with a complex answer…but it all starts with vine size. The chart shows the relationship between vine size and yield under four different pruning practices. The magic yield to pruning weight ratio value for balanced Concord vines in the Lake Erie region is “15” (i.e. 15 pounds of fruit for each pound of pruning weight).

1. Vine capacity and fruit yield potential increase with vine size. This cannot be overstated…if you want to increase the productivity of your vineyard, increase vine size through water and nutrient management.

2. Balanced pruning at 30+10 (i.e. Retaining 30 buds for the first pound of pruning weight and 10 additional buds for each additional pound of pruning weight) is a misnomer because it produces undercropped, not balanced vines. In this case, pruning limits fruit yield and it does not reach the desired 8-10 tons/acre even at the largest vine size.

3. 60+10 pruning is better than 30+10 but still only reaches maximum yield at very large vine size. Vineyards with consistently high vine size (>3.5 pounds) are rare in commercial production situations in NY.

4. 100 fixed node pruning will be overcropped on small vines or poor growing seasons and udercropped on large vines or good (warm) growing seasons. The benefit of 100 node pruning is in the 1.5 to 2.5 pound vine size range where higher yield can be achieved while still maintaining vine balance.

5. High 120 node pruning, similar to what is done in mechanical pruned systems, is almost always overcropped except for at very high vine size. That is why we recomment and practice mid-season crop estimation and fruit thinning in machine pruned vineyards.