The importance of pruning grapevines

Blog In the Vineyard

My first visit to Bordeaux shattered romantic notions of rambling grapevines. Seeing those tightly clipped vineyards, I wondered where all those passionate winemakers had gone, and when the bean-counters had moved in. At the time, we were enroute to Northern Portugal, where vineyards were still growing in wild abandon. It was perplexing. Why do some grapevines enjoy a mardi-gras while others perform a military parade?

The answer is simple. It depends on what’s going to happen with the fruit.

Wine grapes are pruned to produce fewer grapes that are more concentrated in flavour. Table grapes normally have a larger canopy which enables a higher quantity of fruit. Wine Folly describes a difference between wine and table grapes, “A single mature Cowart muscadine (Vitis rotundifolia) table grape vine can produce 15-30 lbs of grapes per vine. A mature Zinfandel (Vitis vinifera) wine grape vine produces about 8-12 lbs of grapes per vine.

Canopy management

The word canopy conjures up images of raucous birdsong, rain forest and jungle monkeys, but it’s also used in viticulture and refers to everything aboveground of the grape plant, i.e. the trunk, cordons, stems, leaves, flowers and fruit. It’s primary function is to capture light energy, regulate water use through transpiration and to create a microclimate to ripen the grapes.

G. Nonnecke defines canopy management as, “Finding the balance in enough foliage to facilitate photosynthesis without excessive shading that could impede grape ripening or promote grape diseases.” Canopy management includes pruning, trellissing and caring for the vines.

Mirabeau’s delicious Provence Rosés fall under the Côtes de Provence AOC [Appellation d’origine contrôlée]. Our wine growers follow the AOC regulations as to how far apart the vines should be planted, how the grape varietals should be pruned, how many buds should be kept, as well as a bunch of other factors. It’s rather complicated but feel free to read the full report (in French) if you’re interested: Côtes de Provence AOC (pdf).

Pruning methods

There are many ways to prune vines, which are chosen according to the type of grape and where the vines grow. In Provence, the common method is Cordon de Royat. Cordon pruned vines are trained on trellises, and have a smaller canopy. These vines can be harvested by hand or machine. You’ll still find the odd vineyard where Goblet pruning has been utilised. It’s an ancient practice, where vines grow independently. Over the years, the trunk forms quite a stump and the growth becomes bushy, requiring harvesting by hand. This informative INRAP graphic shows the differences rather well.

inrapfr-latailledelavigne

During summer, green pruning may take place if the growth is too vigorous to keep the focus and energy on the chosen canes. New buds appear on the current year’s canes and will harden before winter. Pruning is very important, because you’re choosing the buds that will produce the fruit for next year’s harvest. Bud break occurs around Spring, when these hardened buds burst and release water and minerals, a process called “bleeding” that allows new shoots to appear.

Trellising

Trellising is an important part of managing the canopy. If left alone, grapes vines would climb and creep anywhere they wanted. Using trellises, viticulturists can determine the height of the canopy, which makes it easier for the people tending the vines and for leaving enough room in between the rows for machinery. Another interesting advantage of trellising is the protection it offers by keeping the plants off the ground.

Most Vitis vinifera (wine grapes) have been grafted onto resistant American stock after the phylloxera epidemic nearly wiped out European vineyards. The sap-sucking critters feed on roots causing deformations that eventually choke the plant of water and nutrients. The American stock secretes a sticky sap that gets stuck in their teeny mouths and they move away. When canes of the European plant touch the ground, they send out basal shoots or suckers to root themselves, thereby becoming vulnerable to the insects, which would affect both the European plant and American stock.

It’s interesting to note that pruning isn’t necessary; grapes will grow and vines will meander, however if you want to get the best grapes you can, an informed helping hand is needed. After delving into this, I can see how my notion in Bordeaux was misplaced. Winemakers are even more passionate than I imagined, and it’s not the bean-counters that moved in, but rather the bud-counters. All this to ensure that the wine we enjoy is the best it can be. For this I say, “thank you” and while it’s still winter, “at ease, soldier.”

The author: Victoria Koning

Victoria enjoys travel, writing, photography and has oodles of IT experience (technical & software support, web design and online marketing). Born in Cape Town, she worked in Johannesburg, lived in the Netherlands and now calls Cotignac home (see Tours and Tales.com). Inspired by "following a dream" Victoria loves sharing the Mirabeau story and fab wines. Having Dutch as a second language is surprisingly useful.

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