Issue link: http://winesandvines.uberflip.com/i/658375
April 2016 WINES&VINES 73 GRAPEGROWING Put Your Money Precision Frost Protection, Target Those Frost Pockets! READ MORE ABOUT IT AT www.shurfarms.com Where Your Frost Is! SHuR FARMS Frost Protection Colton, CA (909) 825-2035 info@shurfarms.com lated with the tannin concentra- tions, but varied only from about five to not quite seven on a scale of one to 10, while the corre- sponding differences in yield var- ied more than threefold. Yield and ripening To be sure, there are studies showing negative relationships of color or other quality attributes to yield, as predicted by HYLQ. For example, Sauvignon Blanc wine quality scores were highest at the lowest yield (and lowest at the highest yield) in a study that included some (but not all) fruit harvested at the same Brix (see "Wine Quality Scores – Sauvu- gnon Blanc"). The maturity (Brix) of the fruit at harvest is important for understanding the role of yield in wine grape quality, be- cause most viticulture experi- ments harvest all fruit on the same day, but the most common fruit response to yield reduction by pruning and cluster thinning is advanced fruit ripening. Thus, fruit reach ripeness sufficient for winemaking earlier when lower crop loads are carried, and they are riper at a given harvest date. This creates a problem for inter- preting the results of those stud- ies, unless the only quality issue is the advancement of ripening. In experiments with Shiraz in Australia's Barossa Valley, re- searchers Tony Wolfe, Peter Dry and colleagues found a consis- tently negative relationship be- tween fruit anthocyanins and crop yield in three different sea- sons (color decreased as yield increased). In this study, how- ever, sugar accumulation lagged in the higher yielding treatments, making it difficult to know how much of the differences in color were due to differences in fruit maturity. When the fruit of vines with significantly different yields are harvested on the same date, wines made from unripe (higher yielding) grapes are often found lacking. For example, in one early study when crop was thinned, the intensity of "good wine aroma" was dramatically increased, but the higher cropped vines had less mature fruit at harvest. This is consistent with HYLQ, but the aromas probably reflected riper fruit at lower crop loads rather than an effect of yield per se. In most cases, when yields varied but fruit were harvested at the same Brix (rather than on the same date), studies have found little or no significant dif- ferences or loss of quality attri- butes in fruit or wine (as shown in the table "Studies Report Lit- tle or No Effect in Yield, Fruit or Wine Attributes"). However, my analysis is based on what could be gleaned from studies con- ducted for purposes other than testing HYLQ, and it is notori- Expert wine panels assigned scores to Sauvignon Blanc grown in the Golan Heights, Israel, and harvested in 1992, 1993 and 1994. (Naor et al., 2002.) WINE QUALITY SCORES – SAUVIGNON BLANC 13.5 13.0 12.5 12.0 11.5 11.0 10.5 10.0 2 4 6 8 10 12 14 16 Yield (kg/vine)