What are “bull” canes and how do I handle them?

“Bull cane” is the term used to refer to shoot growth that is too vigorous. Bull canes typically have very long internodes (5-6 inches or more), large diameter (greater than ½ inch), and generally are somewhat flattened of two sides, giving the cane more of an oval shape in cross-section, as opposed to circular. They are poorly fruitful or unfruitful, less cold-hardy than normal-sized canes, and make poor selections for trunks, to lay down for cordons or to keep for spurs or fruiting canes. Characteristically, they are found on very and overly vigorous vines and while seeing one here and there is not unusual, the presence of many in a vineyard block (or several on a single vine) indicates a need to devigorate vines. First, make sure that you are retaining enough nodes at pruning (if you are not currently using balanced pruning, consider doing so to ensure that the vines are not being over-pruned). Also, if this condition is very common in your vineyard, re-examine your fertilization and/or irrigation practices. Limit nitrogen applications. This situation is often found on vines in backyard situations where the lawn is watered and fertilized.