By Jen Pfeiffer
As I am writing this, a blustering wind is blowing outside, rain is threatening and it definitely, definitely is cold out there. Sure feels like winter to me, and winter in the vineyard is the time when the grape vines are in dormancy and need to be pruned.
Grape vine pruning is a critical practice of vineyard management, and marks the beginnings of the yearly cycle of the plant. Our pruning helps to control the amount of fruit that is set. By pruning a vine, you are telling it how many bunches of grapes you want it to produce and ripen in the subsequent year.
Pruning prevents the vine from producing too much foliage, which in turn amounts to not enough fruit. A well pruned vine is given the appropriate exposure to sunlight, air circulation and maintenance. These factors are very important in battling diseases and pests, particularly in wetter vintages. Pruning a grape vine correctly will optimise the vine's productivity and fruit quality.
In the Rutherglen region, there are two pruning methods mainly used amongst vignerons. They are spur pruning and cane pruning.
Spur pruning is a popular method as it is cost-effective, easy to do and easy to teach. In some ways, it is like giving the grapevine a short hair cut.
Two permanent branches, or cordons, are retained on the horizontal trellis wire, on either side of the trunk. Each year the shoots, or canes, that grow vertically from the cordons are pruned back to form spurs. The spurs are the small stem where a cluster of shoots grow from. At each spur, the best or closest cane to the permanent cordon is chosen to be pruned back to generally 2 buds. The remaining canes get cut away, leaving each spur with one 2 bud stem. From these 2 bud spurs, the new fruiting canes will grow. Crop load is determined by how many buds to leave per spur and how many spurs to leave per cordon.
Cane pruning is more difficult than spur pruning and costs more money. The advantages are increased frost protection, even production, even spacing of the growing shoots in the spring and allowing good levels of sunlight into the canopy, all of which mean good disease control.
Four strong canes are identified to be left for the following year's crop. These will come from spurs close to the trunk or from the lower part of last year's canes.
All other canes are cut off and removed from the trellis system. Of the four canes left, the strongest two (the fruiting canes) are chosen and then ends cut so that the tip of one cane should meet the tip of the other cane when tied on the wire from the adjacent vine. The remaining two canes are cut back to two buds to form a spur to make "renewal canes" for the year after next.
Finally, the long fruiting canes are wrapped around and tied on to the trellis wire.