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April 2016 WINES&VINES 71 GRAPEGROWING Variety Applying the HYLQ concept in- terchangeably among varieties ignores the biology of what makes one variety distinct from another. There is no biological reason or precedent in other crops that should lead us to as- sume that more yield in a variety is linked inversely and inescap- ably to lower concentrations of flavors in the fruit when com- pared to a lower yielding variety. For example, Petit Verdot is more fruitful (produces more clusters) than Malbec and many other red varieties, yet it has much more red color in the fruit and wines. It is likely that varieties differ in their responses to crop load, but the limited empirical evidence available thus far does not sup- port a high sensitivity in any particular variety. We like wines so much that we try to grow wine grapes everywhere, including locations to which some popular varieties may not be best suited. It is possible that part of what has been attributed to a variety's sensitivity to yield has as much or more to do with the variety interaction with the soil and weather aspects of the environ- ment, about which there is still much to be discovered. Pruning and cluster thinning Pruning and cluster thinning are the most direct and common means for manipulating yield in winegrowing, and they can be adjusted each season. A third means is shoot thinning, al- though this technique is also used to manage the canopy mi- croclimate. When the HYLQ con- cept is raised in discussions of vineyard management, pruning and cluster thinning are usually the implied subjects. The HYLQ myth did not come into existence by mistake; there are studies dating back as far as 1904 containing results and inter- pretations consistent with HYLQ predictions, but the number and history of studies with contrary results are quite surprising. Investigations of putative yield effects on wine sensory at- tributes evidently began in the 1950s at the University of Cali- fornia, Davis (UC Davis), long after the HYLQ myth had as- sumed dogma status. Professors M a y n a r d A m e r i n e , R o b e r t Weaver and others conducted field trials with varied pruning, cluster thinning, or both. They then measured vine yields, fol- lowed a consistent protocol to make the fruit into wine and used the recently developed sen- sory methods to evaluate wine quality. Combining several vin- tages (1949-51), their data show little or no response of wine scores to wide changes in yield (up to a fivefold range of yields) of Alicante, Carignane, Grenache and Zinfandel; however, wine scores for Zinfandel may have decreased at highest yields per vine. In 1961, Amerine and Weaver reported on another set of experiments with Grenache and Carignane that appear to show more sensitivity of wine scores to yield but at much higher yields. The authors con- cluded, "The final wine rating was just as high in over-cropped Carignane vines as in normal- crop fruit, and the difference was only slightly in favor of the nor- mal crop in Grenache." Brian Freeman and Mark Kliewer conducted studies in the early 1980s that manipulated yield via irrigation and pruning in There is no biological reason or precedent in other crops that should lead us to assume that more yield in a variety is linked inversely and inescapably to lower concentrations of flavors in the fruit. SELL TO MORE GROWERS The Wines & Vines Grower Online Marketing System (GOMS) enables users to create and save highly customized grower searches, and export results into advanced report types, data exports and mailing labels. (866) 453-9701 • winesandvines.com/OMS SELECT RECORDS BASED ON: SELECT RECORDS BASED ON: SELECT RECORDS BASED ON: region varietals acreage grape sales new vineyard