In The Vineyard Growing


Tominimize the chance of something going horribly wrong, target the wine style and adjust your vineyard management to fit.


By Gary Strachan


fter reading a book on the biochemistry of sweet wines (see Winemaker’s Bookshelf), I just had to write about the risks involved in growing grapes for sweet wines. Making sweet wines is not for the faint hearted. Many think that making sweet wines is what you do if you can’t find a home for your grapes during the regular crush. Why would anyone purposely take the risk of letting thousands of dollars hang around the vineyard to be consumed or spoiled by every large and small predator or infection that lives on your farm? Have your head read! If you stayed with me for the first two paragraphs, here are some suggestions. Keep the vineyard as clean as your kitchen counter. NO infections. This can be done by using a good preemptive mildew and botrytis spray program. Everyone knows the drill, or you can look it up in the Grape Management Guide: Remove old infected clusters and wood from the vineyard; maintain an open canopy; expose the clusters; watch the humidity and temperature to estimate the risk of infection; botrytis spray before bunch closure; control leafhoppers, mites, and wasps. Do you get the picture? To minimize the chance of something going horribly wrong, target the wine style and adjust your vineyard management to fit.


A


Some grape varieties are suited better for sweet wine production. Clusters should be loose, berries should have a thick skin (resistant to infection), and berries should be moderate in size.


For your site, the variety must be able to ripen fully in an average season. For example, the hybrid Vidal is a popular grape for Ontario icewine, and may be a good choice for some B.C. locations, because it has these properties. For icewine, it is best to choose a late ripening variety so the pedicels are not fully dried out when the vine reaches dormancy, or much of your crop may be on the vineyard floor by harvest. For shorter season varieties, choose a cooler site or carry a heavier crop to delay ripening. Install good netting, surround the site with deer fence and pray for an early freeze. If the choice is to make a botrytis-affected wine, the rules


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sweeter day by day


The difference between Noble rot on the right (dry) and sour rot on the left (wet).


change. Botrytis infection is generally required before bunch closure, so the typical botrytis spray is not applied at that stage.


Ripening conditions in which night temperatures drop below the dew point followed by warm sunny days can make the difference between noble rot and bunch rot. If the vineyard is west-facing, these conditions are more easily attained, but if the weather turns wet and cool pre-harvest, your clusters may turn to mush instead of botrytised raisins. Mid-season varieties that ripen while the daytime temperature is still above 20 degrees are better suited. When harvesting, look at the infected clusters. If they are dry, you’re in luck. If they are wet, the clusters probably have a population of secondary infections and your crop has evolved into expensive compost.. If you are patient, you may be able to hand-select dried clusters to salvage part of a useless harvest. Other methods to create sweet wines are not as risky as long extended hang time in the vineyard. Wine styles such as Amarone or Vin de Paille are traditionally made from grapes dried on straw mats before being made into wine. Outdoors is not a reliable technique for drying at our extreme latitude, but it can be done on trays in a greenhouse. Again, the grape clusters must be scrupulously clean or there is risk of developing mold during drying.


Loose clusters, well spaced on drying racks will accelerate the drying and minimize the chance of spoilage before the grapes evolve into a luscious, concentrated, complex wine. Another class of sweet wines is made from unfermented or partially fermented fruit by fortification with distilled spirit: the ports and mistelles. The grapes for these wines require no special vineyard management beyond choice of grape variety to create the appropriate flavours.


I suppose we could always add sugar. When cane sugar became available it was a revolution in the production of sweet wines. It was far easier to sweeten with sugar than go through the heroics of heat concentrating single strength juice, drying the berries for raisins, or adding honey.


These practices have been part of the tradition of old world winemaking for a thousand years or more and the substitution of cane sugar for the traditional must concentration techniques is still considered to be fraud. Adding sugar is an efficient method to produce alcohol but it doesn’t produce the body, mouthfeel and complexity of the time honoured, inefficient methods.


A quaffing wine can be made with sugar but the genuine product is made to be savoured.


British Columbia FRUIT GROWER • Winter 2013-14


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