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Winemaker Notes, Vineyard Yield - May 2011 I spent a significant amount of time considering vineyard yield, or the lack therof, after the 2008 and 2009 vintages. I believe yield to be an important part of vine management and wine quality. The harvest reports address yield in both 2008 and 2009 because it was lower than normal in 2008 and higher in 2009. The issue setting a target yield is not simple or straightforward. There is no magic yield number. It is also difficult to acurately hit the target you choose. The difficulty in estimating the crop and thinning to acheive to a specific yield is addressed in the 2009 vintage report. A discussion of what yield to target is the subject of these Winemaker Notes. Some believe that lower crops make better wine. That can be true if the vineyard is over cropped and the vine is unable to mature the fruit hanging on the vine. If the yield is too high, the plant is unable to ripen the fruit. Green flavors, unripe tannins and high acidity do not result in good wine. It is not true if the vine's canopy is in balance with the amount of fruit on the vine. My objective in every vintage is to pick fully mature fruit at the peak of flavor development while retaining a core of acidity to support the finished wine. Our target yield varies with each growing season. Lower crop levels accelerate the time of ripening, higher crops delay ripening. This is important because we generally pick Pinot noir between 105 and 110 days from the time of mid-bloom. Cool, wet springs result in a late bloom and harvest will occur later in October. If October is cold and wet, the fruit may never mature. In this situation, we thin to lower crop levels to accelerate ripening, increasing the likelihood that we can harvest before the fall weather fronts end the growing season. Conversely, if the spring weather is warm and sunny, bloom can occur earlier than normal. Ripening is more likely to occur early in the fall when temperatures are warm. Sun and heat produce sugar (higher alcohol) and lower acidity. It does not produce more flavor or balanced wines. The amount of time from full veraison (coloring of the grapes) until harvest is what develops flavor. By targeting a higher yield, we can delay the harvest and mature the fruit more slowly in cooler weather. This will result in more complete flavor development and greater complexity in the wine. It also maintains acidity, critical to food compatibility. Low crops are important, just not too low. The balance point depends on the season, the site, and style of Pinot noir the winemaker wants to produce. I target yields between 2.0 and 2.8 tons per acre. Above 3 tons per acre, the chances of fully ripening Pinot noir in the Willamette Valley decline precipitously. It has happened, but only twice in 23 years. There is an economic impact on yields. Top quality grapes in Oregon are usually contracted by the acre. This allows each winemaker to determine the best viticultural methods and target yields specific to the style of wine they produce. If the price per acre is $7000 and the yield is 2.5 tons per acre, then the cost per ton is $2800. If the yield is reduced to 1.5 tons per acre, then the cost is $4667. The largest cost in making wine is the cost of the fruit. The sum of all the other costs: barrels, bottles, corks, foils, labels, and labor are less than the fruit cost. The more expensive the fruit, the higher the bottle price. The general rule for the price of a bottle of wine is 1/100 of the price per ton of the grapes. If a wine priced at $47 is much better than one at $28, it may be worth the price. However, both these yields can produce perfectly ripe, mature grapes and make similar quality wine. The customer will gravitate to the better value (unless they believe that $$$ equates to quality). I am concerned with quality and value. If the lower crop will not make better wine, then the higher price is not justified. It is the responsibility of the winemaker to look at the season, the site, and the wine style and decide what yield to target. We estimate the crop by taking a sample at the mid-point in the grapes development cycle, at 50 days post-bloom. This is known as "lag-phase" and coincides with seed hardening, the time when the seeds become lignified and harden. I, and other Oregon winemakers, have used this system for many years. We do an analysis of the crop: determine average cluster weight, number of clusters per vine, and number of vines per acre. With this information we calculate the yield at harvest by using a growth factor, usually 2. We then determine how much to thin the crop to achieve the desired yield. Here are two examples. 2008 was a late vintage, the latest in record for Oregon. Mid-bloom occurred at most sites in early July. To increase the chance the grapes would mature, I decided that the crop level needed to be low. My target was 1.8 to 2.4 tons an acre, depending on the site. We did this, thinned in most sites, and picked beautiful fruit in almost perfect conditions. The average time on the vine was 106 days, with harvest between 10/13 and 10/18. 2009 was a early vintage with mid-bloom on June 16th, more than two weeks earlier than in 2008. We targeted yields slightly higher than normal, between 2.4 and 2.9 tons per acre. The average time on the vine was 114 days, picking between 10/2 and 10/10. Again the fruit quality was excellent with attractive, bright fruit flavors and an ample backbone of acidity in the wines. Vineyard yields must be controlled to produce top quality Pinot noir. However, there is no magic number. Adjusting for seasonal variations, variations in vineyard terroirs, and clonal differences is the key to determining the best yield in each situation. A little cooperation from Mother Nature in October also helps. Mark Vlossak, winemaker |
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