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April 2016 WINES&VINES 69 GRAPEGROWING T wo of the most widely accepted articles of faith in winegrowing are that: 1) low crop yields and 2) small berries are key factors in producing the best wines. Both winegrowers and the popular wine press fre- quently invoke the high yield–low quality (HYLQ) and big bad berry (BBB) concepts when discussing wine quality in general, or with respect to specific wines. A visual starting point for examining the HYLQ paradigm is a linear decrease in quality with increasing yield (see Curve 1 in "Hypo- thetical Relationships of Quality Vs. Yield or Berry Size"). In this straightforward hypo- thetical (suggested by many proponents of the HYLQ concept), any increase in yield will result in a sacrifice in fruit and wine qual- ity—but this purported relationship is merely a starting point. The relationship between yield and quality could take many forms, including a very steep slope or an almost flat line, the latter indicating little or no depen- dence of fruit or wine quality on yield. Some claim to have more specific knowl- edge of the shape of this supposed relation- ship or curve. According to Karen MacNeil, author of The Wine Bible, "The relationship of yield of grapes to wine quality is ex- tremely complex and nonlinear." No further explanation of the complexity is offered with that statement, but potentially impor- tant insight is given in her introductory comments about yield and quality: "We do know this: For every vineyard, there is a breaking point—a point where too many grapes will cause the vineyard to be out of balance, and where the subsequent quality of the wine will plummet." Wine journalists James Halliday and Hugh Johnson include a short chapter dedicated to yield and quality in The Art and Science of Wine, in which they claim, "However yield is measured, there is no question of relating it directly to quality." Apparently by "di- rectly," they mean something similar to Mac- Neil, as they cite the "the French rule of thumb" of 3.7 tons per acre as a yield not to be crossed when attempting to produce fine wine. Whereas MacNeil sees this threshold as vineyard-specific, Halliday and Johnson report this as a broader overall principle indicating, for example, that high-quality German Riesling arises from yields similar to those required for Chardonnay in Burgun- dian vineyards. It is interesting to note that the Napa average yield since the 1970s is curiously close to the 3.7 tons per acre stan- dard suggested by Halliday and Johnson. The question is whether trial and error has worked out a fundamental truth, or if a herd mentality is in effect. T h e h y p o t h e t i c a l b r e a k i n g p o i n t — whether for wine grapes in general or for a vineyard—is represented by Curve 2 in "Hy- pothetical Relationships of Quality Vs. Yield or Berry Size," in which the real action in loss of quality occurs above some specific relatively high yield point. If the relationship of quality to yield indeed follows Curve 2, reducing crop below "60" would have no effect on the wine, and hence sacrificing yield would hardly be the virtue that it is generally held out to be (in contrast to C u r v e 1 , w h e r e every reduction in yield brings an in- crease in quality). Additionally, if that hypothetical thresh- old of Curve 2 were known, producers could exploit this knowledge to pro- duce a higher vol- ume of similarly fine wines rather than needlessly restrict- ing production—a practice that itself often costs money. If, alternatively, the quality response i s t h a t s h o w n i n C u r v e 3 , y i e l d s above some inter- mediate value will all produce similar and relatively low-quality wine, and only at very low yields would each incremental decrease lead to an increasingly better wine. The extreme importance of low yields for obtaining high quality that is pro- claimed by some wine writers and producers (and printed on the back labels of some Cali- fornia wines) is reflected in Curve 3. Because the yield must be so low, very little of the high-quality wine could be produced and sold. Curve 3 expresses a very different re- lationship between yield and quality than that described by MacNeil for vineyards or suggested in a more general sense by Halli- day and Johnson. MacNeil gives a measured evaluation of the role of yield in her glossary, noting sev- eral caveats with respect to the HYLQ model. Yet, when discussing the designation of Grand Cru vineyards in Alsace, France, Mac- Neil examines "what, if any, limits should be set on a Grand cru's yield. Clearly, the stricter WHAT IS THE EXPECTED RELATIONSHIP OF GRAPES AND WINES TO YIELD? By Mark A. Matthews Curve 1 represents a direct (linear) dependence of fruit and wine qualities on yield or berry size. Curve 2 represents quality as relatively insensitive to yield or size in- creases up to a point, beyond which quality falls. Curve 3 represents quality as rel- atively insensitive to high yield or big berries, but below some yield or berry size quality becomes increasingly positive with further decreases in yield or size. HYPOTHETICAL RELATIONSHIPS OF QUALITY VS. YIELD OR BERRY SIZE 100 80 60 40 20 0 Wine quality attributes 0 20 40 60 80 1 0 0 Breaking point? 1 2 3 Relative yield or berry size