Pruning vines is essential task

Pruning can start as soon as the grapes have been picked but sensible vignerons would wait until the leaves have fallen so that the vine can build up its store of carbohydrates in its roots, ready for bud-burst in the spring. Usually the new shoots appear from late March to the middle of April.

Vines need to be pruned each year in order to manage the amount of grapes they produce, known as the yield. Grapevines, left to their own resources, produce more bunches of grapes than they have the ability to ripen. So they have to be restricted in order that all the bunches ripen to the required level and all at the same time. Otherwise the resulting wine would be thin and overly acidic.

Bunches only appear on the new stems which grow each season. Each stem usually producing one or two bunches of grapes. So controlling the number of stems will control the number of bunches.

The stems grow from the buds on last year’s stems (known as canes). Therefore all pruning techniques aim to leave only a certain number of buds from which new stems can grow. This ranges from 12 to 24 depending on the yield required, which will have an effect on quality. The higher the yield, the lower the quality as a general rule.

The second aim of pruning is to encourage the bunches to grow in a nicely distributed way so they will not clump together and be prone to fungal diseases and that they will be well exposed to the sun.

However, pruning methods vary by region. The main difference is whether the vines are:

1) Cane-pruned (Guyot): Each year one or two whole canes are retained and all the rest are cut off completely. The new canes are trimmed to a particular length and usually wound around and fastened to a wire.

2) Spur-pruned (Cordon): Once a cane has been in place for a year and produced its shoots, those shoots are trimmed back to leave only two buds. The original cane is then known as an arm or cordon and the short little stumps of last-year’s shoots are known as spurs.

The spur system makes it possible for mechanical pruning. In France this is a preliminary step before finishing by hand but some New World vineyards are pruned only by machine.

In the south of France, many vines are grown without wires in a system known as gobelet. They are spur pruned but the arms are shorter and more vertical.

Cane-pruning is mainly done in the north on varieties such as Chardonnay, Sauvignon blanc and Cabernet Sauvignon. Spur pruning is more common in the Rhône and the south with Syrah and Viognier. Goblet is restricted to grape varieties with very strong, vertical shoots, notably Grenache. The main reasons for the differences are that in cooler climates, the buds do not always produce shoots with bunches on them, especially those two basal buds left on the spurs. Spur-pruning is less time-consuming than cane-pruning.

The specific pruning method used, the number and length of canes or spurs retained is actually part of the requirements for making an AOP (Appellation d’Origine Protégée) wine.

In all cases, each vine needs to be pruned by hand by someone trained in the method. The pruner needs to make a considered choice about which canes to remove and which canes or spurs to keep. They need to keep only the number of buds desired. They need to be careful when tying down to the wires so as not to damage the buds. The old manual secateurs have been replaced by compressed air or battery-powered secateurs but each cut still needs to be made manually.

Pruning is one of the most important jobs in the vineyard year. Doing it badly will affect both this year’s crop and the next. Doing it well is the first step in producing a better wine.

Jonathan Hesford studied oenology and viticulture in New Zealand and is the winemaker and owner of Domaine Treloar in the Roussillon.

www.domainetreloar.com

A year in the vineyard with Jonathan Hesford of Domaine Treloar

The Terroirist