Inside Knights Bridge
Cane and Spur Pruning
With the 2008 vintage wines put to rest for the winter in the cellar, we have turned our attention outside to the Estate Vineyard and the task of pruning our vines. Ask any vineyard crew and they will admit that pruning is a long process, but it plays a critical role in the development and maintenance of the vineyard and the resulting wine...
With the 2008 vintage wines put to rest for the winter in the cellar, we have turned our attention outside to the Estate Vineyard and the task of pruning our vines. Ask any vineyard crew and they will admit that pruning is a long process, but it plays a critical role in the development and maintenance of the vineyard and the resulting wine. Pruning involves the removal of vegetative growth on the vine and usually starts in January or February and continues through harvest. By pruning after each harvest the winemaking team can control the size and shape of the vine. This optimizes production potential, maintains balance between vegetative growth and fruit production, regulates bud break, and can remove diseased tissue. In viticulture terms, there are four categories of pruning: vine form initiation (e.g., cane pruning, spur pruning, etc.), removal of the previous year’s growth, canopy management, and fruit thinning. In the week’s ahead, we’ll post a series of journals to give you an insider’s look at how we keep our vines healthy through these various types of pruning. We’ll start with cane and spur pruning.
Although there are many types of vine forms, two of the most common include cane and spur pruning. Spur pruning creates stationary cordons that are used year after year, where cane pruning uses last years growth to lay new cordons. Spur pruning, most often used for small vineyards, cuts back the previous years canes to leave two buds per spur. These buds will produce two shoots for the current year. Many believe this pruning method results in well distributed fruit with a more manageable canopy. One of the most commonly used trellising techniques is Vertical-Shoot-Position (VSP). This allows more sunlight to reach the fruit and opens the vineyard for better air circulation. An example of spur pruning can be seen in Figure One below.
Cane pruning removes the cordon and uses one of the canes from the previous year as a source for the new growth. The cane pruning method is often more time consuming and can require more skill than spur pruning, due to the stationary nature of the cordons. Because cane pruning allows more buds to remain and disperses the fruit-bearing shoots away from the crown of the vine it is often implemented on varietals that produce smaller clusters (e.g., Pinot Noir, Chardonnay, and Riesling) or when a vine’s yield starts to significantly decrease. When selecting the cane, the vineyard manager looks for one that is round and at least ¼” in diameter. This cane is left on the vine during winter pruning and then in early spring it is tied down. Another benefit of cane pruning is that it can hinder the spread of infection, especially Eutypa. When the previous year’s canes and cordons are removed the infected part of the vine is removed before it has had the chance to spread to the trunk of the vine infecting the whole plant. An example of cane pruning can be seen in Figure Two below. In 2006, Knights Bridge Vineyards was cane pruned to retrofit the old vineyard trellising from Scott Henry to VSP. Again in 2007 the vineyard was cane pruned due to the amount of un-fruiting buds and shoots. Ultimately, some of these vines may be retrofitted to become spur pruned, but for now the cane pruning system seems most appropriate.
This journal highlights many of the pruning practices of Knights Bridge Vineyards. Most vineyard managers, including our own, use these general practices changing things slightly depending on the vineyard site. Information for this journal came primarily from an interview with Josh Clark Vineyard Manager at Clark Vineyard Management, from www.sdaws.org/Growing/Pruning.htm, and information gathered at UC Davis workshops.
Figure 1: The components of a grapevine and an example of what the vine looks like when it is spur pruned.
Figure 2: An example of what a cane pruned vine looks like