It's winter time again and all around the county, pruning crews are busy lopping off old wood and selecting fruiting wood for next season's crop. You can manicure your backyard vines in the same fashion with a few helpful tips. There are many reasons to prune vines including maintenance of vine form, improvement of fruit quality and bud fruitfulness, shoot number reduction and concentration of growth into the remaining buds left after pruning. Pruning is quite easy, but requires a little creativity and patience.
There are two ways to prune grapevines during the winter, spur-pruning and cane-pruning. Spur-pruning is the most common and easier of the two. Spur-pruning generally occurs on vines that have been cordon-trained. A cordon-trained vine looks like "T", where the
Bilateral cordon, spur-pruning |
vertical line is the trunk and the horizontal line is the right and left cordon. The lignified shoots branching off of the cordons are pruned from December through January. Follow the "rule of appendages" to determine the number of buds to leave per spur: three buds if the lignified shoot is thumb sized, two buds if the shoot is the size of your middle finger and one bud if it's pinkie size. The advantage of cordon training and spur-pruning is that the spurs are evenly distributed over the length of the cordons and this reduces bunch crowding and disease. This is especially important for varieties that are prone to bunch rot.
Head-trained, cane-pruning |
When if comes to pruning vines in the backyard, cane-pruning should be reserved for varieties that have unfruitful basal buds and bear little fruit when spur-pruned, such as Thompson Seedless. With cane-pruning, four to six fruiting units, or "canes" branch directly off of the trunk. Generally, the canes are ten to fifteen buds/nodes long. At each winter pruning, the fruit canes that produced the previous year's crop are cut off and replaced by new ones. The new canes arise from two-bud renewal spurs which should also be left during pruning. Following pruning, the canes are tied down to the trellis wire. A more in-depth discussion on pruning grapevines can be found in the book General Viticulture by Winkler, Cook, Kliewer and Lider (1974) or call your local UC Cooperative Farm Advisor.
