Sierra Wine & Grape Growers Association
The Vineyard Year
Spring — finds us in the vineyards, with annual pruning chores. This occurs sometime in February, scheduled after the worst of the winter rains but just before bud-break, to minimize the risk of over-wintering spores of fungi infecting open pruning wounds. The later the pruning is done, the faster the pruning wounds heal.
Most vineyards in the Foothills prune all shoots back to a permanent horizontal cordon, leaving just 2 or 3 buds on each pruned shoot. This is called “spur-pruning” as opposed to “cane-pruning”, where whole canes from the prior year’s growth are selected and kept. Each bud will produce a 3′ – 5′ shoot in summer holding 2 grape bunches. The total number of buds left on a vine is determined by the plant’s vigor — more robust vines can support more shoots, and therefore more fruit, than weaker vines.
Summer — is a busy time! Once spring buds break into leaf, bloom quickly occurs . Zinc is often applied just before bloom. This helps the vines in their “fruit set”, encouraging large and full fruit clusters.
Our most dangerous enemy is not an insect, but a fungus called powdery mildew, well-known to rose growers. Powdery mildew spores overwinter on grapevine wood, when winter rains release them from their pods. This fungus grows and multiplies rapidly once the air temperature passes 50°F. Left unchecked, it attacks all parts of the vine – the wood, the leaves and the fruit, weakening the vine and ruining the fruit. To combat this we must spray. The fungicide of choice is a common organic compound — sulfur. It has no build-up and disappears within 10 days. Most growers use liquid sulfur, mixed with water to the correct level. It is sprayed directly on the vines, on a windless day to avoid spray drift.
And then, too, we labor in the vineyards to “shoot-thin” — remove all extra shoots except those from the buds we selected in February. Limiting shoot growth, and therefore fruit production, to vigor guidelines ensures that each vine’s energy is balanced between shoot growth and fruit production, creating quality fruit.
Autumn — is a frenzy of activity, followed by a great sense of relief. The fruit must remain on the vine to reach its targeted sugar level for premium winemaking. Water is usually withheld to concentrate fruit flavors. Berry and cluster samples are picked and crushed every few days, to be tested for sugar and acid levels with refractometers and hydrometers. Once the grapes reach the levels called for by the winery, harvest begins, and picking starts at daybreak and ends before noon, to keep the grapes cool for perfect wine fermentation.
Winter — ’tis the season when we let our vines rest, often tucked under a soft blanket of snow… And we withdraw to our firesides to analyze our data and plan for the coming year.
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