Crop Management in Grapes – Facts for Fancy Fruit

Crop Management in Grapes

Now that we are past fruit set, it is easy to tell what level of crop we are carrying. With the fairly extensive winter injury this year, many varieties will have a light crop borne on secondary or tertiary shoots. Little if any crop control will be needed in those. However, many of the plantings I’ve seen have a very good crop and some crop control will be necessary to balance the vines. A crop load ratio (yield to pruning weight) of 8 to 12 is a good rule of thumb for vine balance. This means we need to leave only enough clusters to produce 8 to 12 lb of fruit on low to medium vigor vines with 1 lb of prunings. For large clustered varieties such as Vidal and Chambourcin, clusters can weight 0.40 lb. So 10 clusters will contribute 4 lb of yield and we would need 25 clusters to produce 10 lb of yield. Medium clustered varieties such as Chardonel, Traminette, and Noiret will have clusters that weight 0.3 to 0.4 lbs. Small clustered varieties like Foch, Vignoles and Marquette will have clusters that weigh 0.15 to 0.25 lbs. More clusters can be retained on the medium and small clustered varieties. And higher vigor vines would carry correspondingly higher cluster counts.

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