Kicker canes.

Pruning in the Napa Valley is in full right swing now.  I hope to begin pruning Vinoland's black grape varieties today or tomorrow. Vinoland is very fortunate not to have an issue with high vigour in the vineyard.  The vines here are rather well balanced individuals, in part due to the fact that they are head trained and in some part due to the fact that our soil is lousy. Except for one small area that is.  In that particular location the vines are planted a little closer together, one row is cordon trained and, seemingly, the vines have found something particularly appealing to them beneath their roots - so they misbehave.  But, what if high vigour was an issue here, as it is on the highly fertile valley floor?  What could be done to suppress the vigour in the vines at the onset of their annual growing cycle? Planting a cover crop could be one solution, but another approach would be to leave kicker canes on the vines.
A kicker cane (aka a sacrificial cane or a vigour diversion cane) can be very helpful in controlling overly enthusiastic vines. This method involves retaining supplemental, disposable canes at pruning time - at the crown of a head trained vine, or at the apical end of a cordon trained vine.  In the cordon trained vine, a kicker cane takes advantage of a grapevines natural disposition towards apical dominance and can also aid in delaying budbreak. Increasing the number of buds retained per vine has an overall vigour reduction effect as the kicker cane becomes a sink for new growth.  Later, after budbreak, the entire cane will be removed to ensure it doesn't sap too much of the vine's vigour.  In the photograph above it is clear that when the kicker cane is removed only the desired 2 bud spur, on this old quadrilateral-cordon trained vine, will remain.
Okay, that's enough of that, I'm off outside to prune!