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removed after bloom to assist air movement through the canopy and facilitate fruit exposure. Typically, one leaf removed above and below each cluster is sufficient, but on a hot site or if the removal is delayed until the heat of mid summer, even the removal of one leaf may be enough exposure to result in sunburn. In this case, leaves should only be removed on the north and east side of the canopy, to create filtered exposure to sunlight. CS vines typically require no leaf removal because the fruit is borne at the top of the trellis and when canes are repositioned downward, fruit is exposed with filtered sunlight. On a hot site, in a slow growing vineyard there can be enough fruit exposure that sunburn occurs on a CS even without leaf removal. This site may not be suited to CS and the owner should consider a different trellis system.

There can be differences between spur pruned and cane pruned vineyards. In a typical cane pruned VSP vineyard, fruiting canes are spaced at uniform, and close to optimal, intervals along the canopy. The shortest internodes will be at the bottom of the fruiting canes, just below the clusters. Longer internodes will occur in the region near the clusters. In a perfect world, no leaf removal will be required because the longer internodes above the clusters will provide filtered light exposure. If vines are in balance, there may be no need to fruit thin, especially in whites. If the vines have excess vigour, many growers leave extra fruit to absorb that vigour. In extreme cases, the excess fruit may be retained until as late as véraison. The tendency in this case would be to delay leaf pulling until it can be combined with cluster thinning. This is a gamble. Fruit which has had no previous direct sun exposure is more susceptible to sunburn. The later you delay exposure, the greater will be the risk of sunburn. Picture what happens with a VSP spur pruned vineyard. In most cases, there are extra canes which have pushed from basal buds or secondary buds. Post bloom is a good time to go through the vineyard to remove the extra canes and lessen canopy density. You will never have a better chance to combine three tasks into

one than to cluster thin and remove leaves while you shoot thin. There are also other considerations that may not be quite so obvious. If berries are touched, it removes the waxy bloom on the surface. This is a protective layer that guards the berry against dehydration but also against ultraviolet light damage. The flip side of this is that ultraviolet light is lethal to fungi, so

fruit exposure inhibits mildew and botrytis, and is most beneficial to all cultural factors if performed early in the season.

The bottom line is that fruit exposure should be done sensibly and done early in the season. Leave procrastination to the gamblers.

— Gary Strachan can be reached at

BC Wine Grape Council 11th Annual Enology & Viticulture

Conference & Trade Show Monday, July 19 & Tuesday, July 20, 2010

Penticton Trade Show & Convention Centre Highlights

H2S Production during Fermentation Dr. Linda Bisson, University of California, Davis, CA

Terroir and Skin Contact Influences on Riesling Aroma Dr. Uli Fisher, Dienstleistungszentrum Ländlicher Raum Rheinpfalz, Germany

How to Bring Consumers to the Premium Price Range Elizabeth Slater, In Short Marketing, California

Vineyard Cover Crops and Floor Management Glenn McGourty, University of California Viticulture Farm Advisor

Vine Water Relations (varietal differences) Dr. Hans Schultz, Geisenheim Research Centre, Germany

Stuck Fermentation and its Relationship with Nutrition Dr. Charles Edwards, Washington State University, Pullman WA

Grapevine Nutrition Stan Grant, Progressive Viticulture, Turlock, CA

Sustainable Pest Management Dr. Tom Lowery, Pacific Agri-Food Research Centre, Summerland BC

Surprising New Irrigation Management Effects On Fruit Quality Dr. Kevin Usher, Pacific Agri-Food Research Centre, Summerland BC

Sustainable Pest Management Dr. Pat Bowen, Pacific Agri-Food Research Centre, Summerland BC

Effect of mixed Saccharomyces cerevisiae strains on Pinot Noir wine complexity Emily Tyrell, University of British Columbia, Vancouver BC

Workshops/Panels • How to promote your brand • Roundtable Beginner’s Guide to developing a safety plan and be Audit Ready • “Information update on Pristine Fungicide, Chateau Herbicide, and Clutch Insecticide- Proper use, timing and application

• Riesling Sensory Workshops and more… Visit the Tradeshow - Over 108 exhibitor floor displays

For more information contact BC Wine Grape Council, Tel: (250) 767-2534 E-mail: or visit:

British Columbia FRUIT GROWER • Summer 2010 27

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