Following the Growth of the Vine

The early stages of shoot positioning – Barlow Homestead Pinot, May 2015

Earlier this year, Jr and I visited with Paul and Kathryn Sloan of Small Vines to track green pruning and bud break at their Barlow Homestead Vineyard in the heart of Green Valley. Jr created a video interview of Paul on the two viticultural events, which you can view here: http://wakawakawinereviews.com/2015/04/06/a-year-with-small-vines-bud-break-green-pruning/

In May, and earlier this month I returned to track two different phases of shoot positioning with Paul. In a cane pruned vineyard relying on vertical shoot positioning, repeated passes for shoot positioning serve as an essential step to the health and balance of the vines offering ample air flow and canopy management for the developing clusters.

The following shares an overview of the process and a look at the importance of shoot positioning in the midst of a year’s vineyard management.

Shoot Positioning

getting ready to shoot position: (from left) Bryce Potter, me, Paul Sloan, May 2015

In a cane pruned, VSP trained site, shoot positioning serves as the next step after green pruning. While green pruning forms the basic architecture of the vine, shoot positioning manicures and directs the growth of the vine. Shoot positioning, then, occurs in multiple steps through vine growth.

The timing of shoot positioning depends on the growth of the vineyard in the particular vintage. 2015 brought a challenging spring for vineyards in Sonoma. With warm January and February weather, growth came early to the vines bringing early bud break and shoot growth. April and May then cooled off significantly, generating what is known as Spring Fever in many Pinot vineyards through the region.

Spring Fever + Frost Damage

Spring Fever is caused by the vine starting to grow from warm weather conditions, and then shutting down again when temperatures drop. Nitrogen gets locked into place in the vine, which in severe cases can lead to nitrogen necrosis in the leaves. In milder cases, as new leaves develop the vine recovers photosynthesizing through the upper leaves. Even so, with Spring Fever, vine growth is slowed – colder temperatures slow vine development, and in the case of nitrogen necrosis the vines ability to photosynthesize is impacted through leaf loss.

Frost damage can also show in damage to vine tips. When temperatures are cold enough, frost effectively singes vine tips, turning them brown and stopping shoot growth. In such cases, secondary shoots will sometimes push from the trunk of the vine becoming the focus for vine development that year.

Shoot Positioning 

Paul Sloan shoot positioning Barlow Homestead Pinot, May 2015

In vertical shoot positioning, shoot growth is managed through a series of steps moving wires into ever higher positions as the shoots get taller, or through tucking shoots between wires. Wires are placed on the trellis system in pairs that effectively create a sandwich around shoots as they grow, with one wire at the front and one at the back of the training system and shoots growing between.

Generally, moving wires is more desirable than tucking shoots as it is faster. In moving wires, however, it is important to be careful to avoid pulling leaves or breaking shoots. As vines grow, their tips and leaves will sometimes wrap wires, or other shoots. This must be managed when moving wires to avoid damaging vines. Tucking vines, on the other hand, is generally done for specific vines rather than entire rows and includes the risk of damaging shoots through breakage.

Wires are placed at the right height to support shoots maintaining a vertical position. Then shoots are spaced at approximately a hand’s width apart with clips used to hold the shoots in the best position between wires. The clips can be moved as needed to adjust to vine growth.

clips used for shoot positioning. The C-shaped clips are biodegradable natural fiber and are used for when wires need to be held close together to maintain the shoot to secure the its position. 

The reusable black clips offer more flexibility and can be used to loop a shoot exactly in place, to offer wider spacing between wires, or to wrap a wire for even closer spacing. 

As vine growth continues, shoot positioning is revisited again and again to keep shoots about a hand’s width apart (in order to keep clusters about a hand’s width apart), and to manage any secondary shoot growth. Rows are approached individually. Wires can be positioned as is appropriate to vine growth in that particular row, or even partial row. Then, vines are clipped individually.

Ideal shoot position depends on the architecture of the particular vine, however goals remain consistent in each case. The goals of shoot positioning include a balance of air flow and leaf shade for clusters. The balance of cluster count per vine is generally established in the earlier step of green pruning as the number of buds allowed to grow determines cluster potential. How that balance is achieved depends upon goals of the farmer such as overall yield, and goals of the winemaker such as wine style.

When it comes to recognizing ideal shoot positioning in the vineyard, Sloan emphasizes the importance of knowing your vineyard. “There is no one right formula, one right thing to do. You have to read your vines, your vineyard. The more you pay attention, the better decisions you can make.” Sloan explains.

The frequency with which Sloan revisits shoot positioning in his Small Vines-managed sites allows him to rely on organic viticulture as well. The attention given to architectural points such as ample airflow and canopy management also serves his ability to keep track of overall vine health, and issues such as disease or insect pressure.

Vine Health and Flavor Development

Paul Sloan discussing cover crop choices in Barlow Homestead, May 2015.
Cover crop through Spring is valuable in organic viticulture as it supports soil health and also offers a habitat for beneficial insects. Vines are most susceptible to harmful insects in Spring, so planting cover crops between rows plays an important role in vineyard health through the balancing of insect populations.

Effective canopy management supports the overall health of the vine reducing disease pressure while also encouraging flavor development.

“What is important about shoot positioning for the organic farmer,” Sloan explains, “is to have air flow through the leaves and clusters.” How such air flow is achieved depends on the overall architecture of the vine.

In vines that include higher cluster count, air flow must be encouraged through leaf removal — too much of both fruit and vegetation doesn’t allow enough air flow — which also has the effect of increasing sun exposure to clusters. On the other hand, to preserve canopy for shade while maintaining air flow, the vine must be shaped in such a way as to reduce cluster count and manage leaf position.

In the case of Small Vines, Sloan chooses to reduce cluster count per vine and focus on high density planting. High density planting reduces the soil nutrients and water supply available to any particular vine, slowing growth, reducing cluster count and leading to a sense of density in the fruit profile.

The Role of Sunlight on Fruit Development

Pinot in Barlow Homestead, early June 2015 (getting ready to do another pass of shoot positioning but note the architecture of the vine places shoots and clusters about a hands width apart)

Sloan clarifies that air flow is not the only factor relevant to shoot positioning. “Even more important than air flow is sunlight. You want sunlight on every leaf, on every shoot” but not on every cluster. Sunlight on the leaves encourages photosynthesis, and therefore also vine growth and fruit development. Direct sunlight to clusters, however, changes the flavor profile of the fruit as well as the fruit structure. To put that another way, directing sunlight to leaves and away from clusters tends to keep flavors in the fruit fresher and brighter. (To read more on the role of sunlight in flavor development, see the following profile on Andy Smith of DuMOL: http://wakawakawinereviews.com/2015/04/13/deepening-dumol-a-day-in-the-vines-with-andy-smith/)

Early sunlight on clusters often encourages thicker skin development (and therefore also more tannin profile), later sunlight on clusters changes the flavor profile of the fruit. Generally you can think of this sort of sun exposure as making flavors darker, moving flavors from fresh fruits to cooked fruit and kitchen flavors (such as caramel in the case of Chardonnay, for example). With reduced sunlight exposure on clusters, canopy management to promote air flow and reduce disease pressure becomes even more important. In this way, shoot positioning plays a role in both farming methods and wine style.

Vine Health and Wine Quality

Vine health also ultimately impacts wine quality. As Sloan explains, “The reason I am so emphatic about making wine from the vines I grow is because if I can keep walking vineyards, and I can move my crew where they’re needed, then I can affect wine quality directly.”

Sourcing fruit from multiple vineyards can be an excellent way for winemakers to get to know and express the signature of a region. Once a region is known, understanding the attention of a particular farmer is the next step to managing wine quality by finding an alignment between farming style and winemaking goals. In the case of Small Vines, Sloan develops and manages vineyard sites for others and makes his Small Vines wines from his own sites.

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