Canopy Management

The goal of vineyard production is vine balance, where adequate canopy size and sunlight exposure give more favorable and sustainable vine growth and fruit quality. Leaves on the outer surface of the canopy absorb or reflect more than 94% of the sunlight that hits them, and less than 6% of the light reaches leaves in the interior. Leaves under one or more layers of other leaves do not work to their full potential and become net users of nutrients rather than producers of carbohydrates; when they are too unproductive, they turn yellow and fall. In highly vigorous vineyards with dense canopies, fruit can have high pH and unripe flavors from compounds such as methoxypyrazines or C6 alcohols, while open fruit zones with well exposed fruit can give higher sugars, color (anthocyanins) and positive aroma and flavor compounds such as norisoprenoids and terpenes. Having too little canopy and overexposed fruit can also have negative results on vine health, productivity and fruit quality.

• Vine balance is the state at which vegetative and reproductive growth can be sustained indefinitely while maintaining healthy canopy growth, adequate fruit production, and desired fruit quality (sugar levels, acid balance and flavor compounds)
• Light on the shoots matters for next year's crop too: buds that develop on shoots in dense, low-light canopies have fewer inflorescences (flower clusters) per shoot than buds on better exposed shoots
• Crop level is part of the same balance, and Oregon State University Extension notes: "There are no set crop levels that will guarantee the best fruit quality."
• Nelson Shaulis showed in the 1960s that canopy management, exposing leaves and grapes to dappled sunshine, could be the key to improving both yield and quality; Richard Smart developed that work in New Zealand from 1981

The general principle is that the more nodes left on spurs or canes, the more potential yield, and retaining more buds at pruning generally leads to increased cropping levels and shoot crowding. Dormant pruning should remove most unnecessary buds before bud break.

• Cane pruning removes most of the previous year's growth and retains only a few long canes and short spurs; it is commonly used for table grapes and some wine grapes in cooler climates like Oregon
• Spur pruning retains short, two-bud spurs along permanent arms and is typically used for wine grapes and muscadines in warmer regions
• Cane pruning may also be necessary for varieties with known low basal bud fruitfulness; in regions with warm springs and summers, spur pruning is acceptable

Shoot thinning is done shortly after budbreak and before shoots are 6 inches long, so shoots can be removed easily without pruning shears and without damaging other shoots. Removing extra shoots increases air flow and canopy sunlight exposure, which helps reduce disease issues when combined with a preventative fungicide spray program. Shoot thinning has been shown to result in higher Brix and pH in the fruit and sometimes an increase in berry skin phenolics and anthocyanins, likely from a combination of managed crop levels and increased sunlight exposure. Hedging is a common practice for VSP-trained vines in Oregon: the goal is to remove excess primary and lateral shoot growth from the top and sides of the canopy, to prevent shading and entanglement of shoots between rows and to allow worker and tractor traffic.

• Oregon State University Extension gives a typical recommendation of 3 to 5 shoots per linear foot of row, and a good target of 3 to 4 shoots per linear foot of canopy for single canopy training systems; the AWRI recommends 15 shoots per metre of single canopy for controlled hand-pruned canopies, with higher numbers possible for hedged vines
• Hedging does not directly decrease the vine's inherent vigor, and in vigorous vines hedging in early to mid-summer can further promote growth by inducing lateral shoot growth
• Hedging too early in the growing season should be avoided, as it can initiate lateral growth and increase canopy density

Cluster zone leaf removal is typically done in and around the cluster zone to allow varying levels of sunlight exposure and air flow. When performed early in berry development (at or before fruit set), leaf removal can increase production of secondary metabolites in the berry, and Oregon research has shown that early leaf removal can increase the color (anthocyanins) and aroma compounds of Pinot noir. Research in Oregon in both warm and cool seasons also found that while leaf pulling can enhance fruit composition at harvest, there is rarely an appreciable difference between leaf removal and no leaf removal on basic ripening parameters including Brix, pH or titratable acidity. Leaf removal before fruit set may reduce the carbohydrates available to the developing flower and may result in lower fruit set.

• Timing (Oregon State University Extension recommends leaf removal on vines where clusters cannot be seen): any time from bloom to just after fruit set; not after berries have grown bigger than pea size; and not waiting until veraison, as late-season leaf removal can lead to sun or heat burn of the fruit if high temperatures occur
• Oregon trials found that typical leaf removal (about 50% of leaves) and up to 100% of cluster zone leaf removal from bloom to pea-size berries did not result in sun or heat burn of fruit, even in warm, dry seasons
• Most growers begin removing leaves at the fruit set or pea-size stage and often remove leaves only on the morning-sun side of the vine, keeping leaf cover over the fruit on the afternoon-sun side to prevent burn
• Leaf removal can be done by hand or by machine; machines use pulsed air or suction and cutting, and hand removal can cost more but cleans the cluster zone more precisely
• Weak or small vines without much canopy density usually have visible clusters, and leaf removal is not necessary

A less dense canopy allows more air flow, faster drying of leaves and better spray penetration, which creates conditions less conducive to disease and improves the efficacy of pesticide applications. Canopy practices let airflow and fungicide sprays penetrate the canopy and give good coverage of the inflorescence or fruit cluster. Botrytis bunch rot, caused by the fungal pathogen Botrytis cinerea, can infect as early as bloom but may not be visible until ripening begins, especially with rain events. In Willamette Valley studies, fruit zone leaf removal reduced the incidence and severity of both powdery mildew and Botrytis bunch rot compared with vines given no leaf removal. Climate changes the calculation: cool climate regions like the Willamette Valley generally need more leaf area to fully ripen fruit than warmer climates with more light intensity and heat units, and leaf removal should be done with caution in the warmer, drier regions of southern and eastern Oregon.

• In hot weather, canopy techniques can be varied by side of the canopy, to minimise direct exposure of bunches to sunlight on the hotter afternoon sun side while still encouraging air flow into the canopy
• Planned wire lifting or leaf removal that could increase bunch exposure should be delayed until after a heat event
• The benefit of more aggressive leaf removal in cool years is more airflow and exposure to aid disease prevention

The majority of vineyards in Oregon are trained to vertically shoot positioned (VSP) systems, and canopy management practices are needed to some degree whatever the vine balance. VSP is suited to mechanisation since the fruit is found in one zone only. Other systems include the Lyre, Geneva Double Curtain (GDC), Scott Henry and minimally pruned systems. Drones and satellite imaging are now used to create detailed aerial maps of vineyard canopies.

• Modified trellising systems can provide increased leaf exposure, decreased canopy density, improved bunch exposure, better spray penetration, lower incidence of pest and disease, and improved yield
• NDVI (normalised difference vegetation index) highlights differences in plant vigour across a site: areas of low vigour might point to issues with soil, pests or disease, while vigorous growth may indicate excess water or nutrients
• These maps help growers prioritise where to intervene and where to hold back

Primary sources: https://extension.oregonstate.edu/sites/extd8/files/documents/lommena/em9071.pdf, https://extension.oregonstate.edu/sites/extd8/files/documents/em9068.pdf, https://extension.oregonstate.edu/crop-production/wine-grapes/how-prevent-botrytis-bunch-rot-vineyard, https://extension.oregonstate.edu/video/how-shoot-thin-grapevines-spring, https://extension.oregonstate.edu/sites/extd8/files/catalog/auto/EM9534.pdf, https://wine.wsu.edu/viticulture-enology-extension-news-fall-2014/. Secondary sources: https://www.awri.com.au/wp-content/uploads/2014/09/on-farm-trials-manual-2-6.pdf, https://www.awri.com.au/information_services/ebulletin/2024/12/19/managing-vineyards-during-hot-weather-conditions/, https://www.wsetglobal.com/knowledge-centre/blog/2025/drones-robots-and-how-vineyard-technology-is-getting-smarter, https://www.jancisrobinson.com/articles/dr-richard-e-smart-1945-2025. Last verified 2026-11-02