topped meristems (the growing point at the tip of the canes).
Irrigation control plays a large role in the attainment of early fruit maturation. Prior to fruit set, grape vines grow rapidly and require adequate water. After fruit set, cane elongation declines and much less water is required. In late summer, prior to veraison, water requirement slows to a trickle (no pun intended – well almost. . . ) but after veraison, a moderate level of irrigation is required in order to balance evapotranspiration loss. As always, each site has unique irrigation requirements according to the water holding capacity of the local soils and the size, age, and vigour of the vines. It isn’t enough to set an irrigation timer at the start of the season. Irrigation timing must be tempered with intelligent observation of vine performance at each growth stage.
The most common way of measuring potential vineyard performance is the Growing Degree Day. This is the mean of the high and low temperature each day, less 10 degrees. The reason for the 10-degree correction is that grapes have negligible metabolic activity below 10 degrees. During this season, we had below-average degree day accumulation during the spring and summer, but above-average in the fall. Superficially, it would seem this would enable vineyard development to compensate by the end of the season, but this argument ignores the development stages (phenology) that grapes pass through each season. In the fall, growth has essentially stopped and the vine is preparing for dormancy. Except for the
accumulation of sugar and secondary metabolites, warmer temperatures have little effect on berry development post-veraison. The above normal fall heat units were too late in the year to compensate for arrested development pre-veraison.
To many, the 2011 season was a wake-up call. It is always tempting to push the limits with location and grape varieties. It’s tempting to plant a longer season variety on a site where they will usually ripen, but it may not be worth the risk in cool years when there is no chance to achieve full maturity. Perhaps the extra market value will compensate for an occasional crop failure. How much of a gambler are you?
— Gary Strachan can be reached at
gestrachan@alum.mit.edu .
British Columbia FRUIT GROWER • Winter 2011-12
Looking Back Originally
begun as Domestic Wines and By-products Limited in
Kelowna in 1932,
the company changed its name in 1936 to Calona Wines and it remains a prominent name on British Columbia’s winescape.
From the beginning, marketing of KELOWNA PUBLIC ARCHIVES PHOTO NO. 8589
the winery’s products has been an important part of building the business, and this photo, probably from the 1940s, shows the range of products the company had begun to make. Sadly, few of these early labels remain to help tell the story of the burgeoning grape and wine business that now boasts more than 175 wineries in the province – most of them located in the Okanagan Valley. — Wayne Wilson is executive director of Kelowna Museums.
For top-quality vineyard equipment Leaf Remover
Rotary Blade Vine Trimmer
Piggy-back Sprayer
Suckering Machine
Munckhof Manufacturing Box 308,
Oliver, British Columbia V0H 1T0 Tel: 250.498.4426 Fax: 250.498.4460
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