A Guide to Canopy Management | March 2001
All winemakers have made the statement, “Wine is made in the vineyard.” This very romantic notion can only be implemented by vineyardists with great management skills, a good sense of timing, experience and most importantly, lots of labor.
At Linden Vineyards we follow a regime of canopy management that is implemented by most premium winegrowers worldwide. It is not magic, it is not revolutionary, it is expensive, and it works. I have included the timing of each procedure according to vine development stage and the calendar (for a typical season in the mid Atlantic). We are not mechanized, so I have also included an approximation of the number of hours per acre required.
The goal is to have a canopy that is uniform, thin, and open to sun, air flow and spray coverage. Worldwide these techniques have proven to produce the best wines possible from a given site. East of the Rockies we find that this not only produces outstanding wines, but also gives us the best tools to manage the fungus diseases and winter hardiness concerns that are not an issue to most of the rest of the grape growing world.
Pruning and Dormant Tying
The goal of pruning is to maintain the shape of the vine to conform to a given training system, trellising, and canopy shape. It is also a rough, first attempt at crop control. Uniformity is the most important aspect. Distances between spurs or canes should spread the resulting shoots evenly along the trellis. Buds should all originate at the same height. “Climbing spurs” that can push their shoot growth into the upper extremes of the canopy should be eliminated. Finally, balanced pruning, adjusting the number of buds left on each vine according to last year’s vigor can help remedy any inconsistencies within a given block. With all of this the goal is to begin the growing season with new shoots that are evenly distributed along the trellis wire and at the same level. Pruning and dormant tying times vary greatly according to training system, vine density and vine age. 30 to 60 hours per acre is our range at Linden.
Timing—when shoots are 4″ to 8″ in length (May). The removal of undesirable shoots early in the season is absolutely necessary to maintain a uniform, light penetrating canopy.
Our goals are to remove:
- Shoots at the base and trunk that will not be used for any trunk renewal (suckering)
- Unfruitful shoots (unless retained for future cane or spur renewal)
- Shoots growing in the wrong direction for the training system (i.e. inward growing shoots in a GDC or Lyre system, or downward growing shoots in a VSP).
- Shoots from areas that are too dense in the canopy. We look for a density of 3 to 6 shoots per foot of trellis depending on the variety, vigor, and yield goal. This, after pruning, is our second crop reduction technique. 5 to 10 hours per acre.
Timing—pre-bloom through the shoot elongation period (late May through July). Even the most basic training systems need some sort of shoot positioning to maintain the desired shape. The 4 systems commonly used are:
- Tucking: Two parallel “sandwich wires” are typically located about 18″ above the fruiting wire (in upward-trained vines). At the right time the shoots are positioned or tucked between these two wires. As with all shoot positioning techniques, timing is critical.
- Tying: Twine or tape is used to secure each shoot to the wires. This is very expensive in terms of labor, but also the most precise in achieving the most uniform canopy.
- Movable catch wires: There are several systems that position shoots upwards during the growing system as wires are physically moved from the ground, and attached to the posts, lifting up wayward shoots.
- Combing: Used on downward growing systems typically around bloom time, once the shoots become less fragile, but before the tendrils become too tenacious. Many shoots want to grow sideways, causing dense, unwieldy canopies. All shoots need to be straightened, or combed downwards to get uniformity of light and spray penetration.
Shoot positioning requires 20 to 60 hours per acre depending on the system and fastidiousness of the grower.
Beginning 10 days after bloom (at shatter or mid June in Virginia) and throughout the season as needed. The goal is to open up the area around the clusters for good airflow (drying), some sun penetration and spray coverage. The timing, intensity and frequency depend on variety, rainfall, vigor, training system and wine style goals. We first started leaf pulling in 1989 and our wine quality improved dramatically. I am still learning about timing and amount of pulling for each vineyard block and growing season. Leaf pulling seems to be especially important to good wine quality when vines are in their awkward, vigorous “teenage years” (5 to 10 years). We typically make 1 to 3 passes per season in an attempt to fine tune as the character of season unfolds. 5 to 15 hours per acre per pass.
Begins once the shoots attain their maximum desired length typically 4 to 5 feet or 12 to 15 leaves per shoot. Mid June to mid July as needed (one to three passes needed, usually rainfall dependent). 1 to 5 hours per acre per pass.
Beginning 10 days after bloom (at shatter or mid June in Virginia) and throughout
the season as needed.
The goal is to open up the area around the clusters for good airflow (drying),
some sun penetration and spray coverage. The timing, intensity, and frequency depends on variety, rainfall, vigor, training system, and wine style goals. We first started leaf pulling in 1989 and our wine quality improved dramatically. I am still learning about timing and amount of pulling for each vineyard block and growing season. Leaf pulling seems to be especially important to good wine quality when vines are in their awkward, vigorous “teenage years” (5 to 10 years). We typically make1 to 3 passes per season in an attempt to fine tune as the character of season unfolds. 5 to 15hours per acre per pass.
Cluster Thinning/Green Harvest
Typically done just before or during verasion (mid July to mid August). The goal is to prevent excessive cropping of the vine (over cropping) and to eliminate less ripe clusters. Overcropped vines produce poorer quality wine and are more subject to winter damage and decline. There are no formulas as to the best yield per vine or per acre. Young vines, drought stressed vines, and low vigor vines often have to be cropped thinned early in the season so that cluster formation does not compete with vine vigor. I prefer to wait as long as possible with “normal,” mature vines. I have found that if the clusters are removed just before or during verasion, berry size is smaller, leading to less compact clusters and less rot. I can also better estimate the crop size and I have a better feeling for the season and the vine’s ability to ripen its crop. Of course with red-fruited varieties there is the extra advantage of cluster thinning at verasion, visually greener clusters can be removed to achieve more uniform ripening. 5 to 20 hours per acre.
In a typical year, If any one of these steps are ignored it will have a detrimental effect on quality. Labor costs alone can be well over $2,000 per acre. The winegrower has to be absolutely convinced that these methods will improve wine quality commensurate with the costs and effort. Then it can truly be said that the wine is made in the vineyard.
Wine East, March 2001