Harvest 101: The Basics of Crush Season (by winespectator.com)

Posted: December 4, 2012 by wynmaker in Farms, Oenology, Vinification, Vintage, Wine, Winemaking, World wine news
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From grape to wine!

From grape to wine!

 

Learn what goes on in the vineyard and winery during each stage of the annual harvest for wine grapes

 

Sports teams have playoffs. Students have finals. And for winegrowers, the big sink-or-swim moment—the event the whole year’s efforts have led up to—is harvest.

The period culminating in grape crush begins when the grapes start to change color in mid to late summer. The actual picking of the grapes usually happens between August and November above the equator and February to April below. What happens in between is the greatest determinant of a wine’s quality in a given vintage. Read on to learn about the processes—and perils—of harvest season.

The Metamorphosis—Veraison
Grape ripening begins with the growth period known as veraison, when the fruit hanging on the vines transforms from small, green, hard berries into what we recognize as grapes. Vines enter this stage about 30 to 70 days, depending on variety and climate, after fruit set (when fertilized flowers have fallen off and become tiny grape bunches)—typically in July or August in the Northern Hemisphere and January or February in the Southern.

During veraison, the grapes lose their bright green color and begin to take on mature hues—from greenish yellow for some white varieties to red, purple or almost black for red varieties. The grapes also soften and rapidly increase in size as the vine begins to pump sugars into the fruit, while acidity starts to decrease. Veraison doesn’t happen at the same time throughout a vineyard, or even for all grapes on a vine or within an individual bunch; those exposed to more sun and warmth get a head start on the grapes in shadier, cooler areas.

Striking a Balance—Controlling Crop Size
Unlike most farmers, top grapegrowers generally seek to limit their yields. That’s right: They want less of the thing they’re going to sell. Why? Because they believe that if the vine is carrying fewer bunches than it is capable of, those grapes will ripen more fully and be higher in quality.

If a crop looks to be too large at veraison, or if ripening has been delayed due to poor weather, a grower will sometimes thin the crop, or conduct a “green harvest.” Vineyard workers cut unripe bunches from the vines; in theory, each vine’s resources are then devoted to the remaining bunches, speeding ripening.

On the other hand, a grower doesn’t want too many leaves per grape bunch. Leaves look pretty, but they can get between the grapes and the sun; too much shade can also promote rot and mildew on bunches. If the weather has been particularly cool, cloudy or damp, growers may remove leaves around the grapes to promote ripening and air circulation.

Pest Busting—Protecting the Crop
Along with the threat of poor weather, grapevines face harassment from various organisms—insects, mildew, rot, other fungi, bacteria and viruses—that can damage fruit, reduce yields or even kill the vines. And just as the grapes ripen come the birds—and deer, bear, wild boar and other hungry animals.

What can be done to protect the vines? Among other things, growers can apply pesticides and fungicides (ranging from copper and sulfur to synthetics), control the canopy of leaves so that wind can dry moisture on the grapes and attract natural predators like bats, insect-eating birds and beneficial insects that eat the vine pests.

Strong fences can keep out four-legged animals, but not the airborne. For flocks of birds, who like a tasty Cabernet as much as anyone, the heavy artillery is wheeled out. Some vignerons shell out to cover all their vines with bird nets, or hire falconers to patrol vineyards with birds of prey. Others rely on bird bombs and bird cannons. Don’t call PETA just yet: These devices don’t actually blast the suckers out of the sky, they merely fire off loud booms that scare birds away.
Read on …

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