It is misleading to superimpose yield levels from one growing region onto another because one size does not fit all. Pontallier points out, “Yield is one important factor of quality not only in Bordeaux but everywhere in the world—but it is not necessarily the same limit everywhere.” The limit depends on factors such as climate and grape variety. Lemon explains the difference between warm and cool growing regions, “In warmer climates with greater numbers of days of direct sunlight you can you hang a larger crop and you can ripen it and the vine won’t struggle. As you move into more northerly climates where you have less days of solar exposure, the same size crop will overload and stress the vine making it unable to produce a quality crop.” Dokoozlian contrasts the conditions in California with those in France, “Look at the huge difference in solar radiation, we’re 25-30% warmer in our premium growing regions. We have a much more stable climate, our latitude is different giving us greater day length and sun exposure. All of the conditions in California are conducive to growth while the conditions in France are much less so.”
Moueix’ contrasts Bordeaux with California based on his experiences at Dominus with similar grape varieties but different climate, “In very hot vintages in Bordeaux, like 1947 and 1989, we can afford slightly bigger yields. But to make a good wine with the weather conditions we have in Bordeaux, which is always limiting in terms of heat, it is critical to keep yields lower. In Bordeaux, we cannot produce good wines above four tons/acre (60hl/hec) and we cannot produce great wines above 3.5 tons/acre (50h/h). The top equilibrium for me in Bordeaux is between 2-3 tons/acre. In California, I think the fact that we can afford bigger yields is due to a completely different weather pattern, and different quality of the soils; I think we need bigger yields to make better wine. At least in the soils I know, which are rather rich soils, at 2.5 tons/acre, which for instance, were my first years at Dominus, the wines were too tannic. I find the equilibrium is roughly 1 ton above Bordeaux—3.5 tons/acre (50h/h) is the best, and we can produce good wines up to 5 tons/acre (70h/h).” While Lemon agrees with Moueix’s comments as they relate to Cabernet Sauvignon, he believes they do not apply to Pinot Noir. To make great Pinot Noir, similar yield levels are necessary in both Burgundy and California.
Pontallier discusses the importance of keeping yields low in a cool growing region like Bordeaux, “If climatic conditions are wonderful in Bordeaux, we can have higher yield and make great wine until 60h/h. One of the greatest vintages we had in the last twenty years was ‘82, a year of very high yields, close to 60hl/hectare. But if climatic conditions are very difficult, if you have controlled your yield under 40hl/hectare, you can make very decent wine. But if you overproduce, you have no chance to get your grapes ripe.” He adds, “And that is why we try to keep—in our conditions in Bordeaux—yields not as low as possible, because that makes no sense. But in our conditions, with our terroir, with our average climatic conditions and with our viticultural practices, our experience shows that in most vintages, between 40-55hl/hectare (3-4 tons/acre), you work very well.”
In addition to climate, grape variety is another significant factor in determining crop levels. White grapes can support a larger crop better than reds, a fact that is written into Burgundy’s Appellation Controlee laws. Chardonnay in particular, can tolerate higher yields better than other white grapes because it is such a neutral aromatic variety, easily influenced by winemaking practices. Mondavi’s Bledsoe comments, “Some producers use high-yielding clones, pick late to maximize flavors thus producing higher alcohol wines. Combined with sur lie aging, new oak and malolactic fermentation, these are ‘in your face,’ reserve-style Chardonnays that are getting high scores and that people love.”
For red varieties, in addition to ripeness measured by brix, pH and acidity, ripeness of tannins or physiological ripeness, is indispensable to quality. Since extra crop delays ripening, underipe tannins means a hard, astringent or vegetal wine. If a grower waits until the tannins are ripe, sugars may be too high and acid too low resulting in an alcoholic, flabby, even prune-like wine. This is a greater risk in warmer climates such as California as Lemon comments, “Overcropping delays maturity. Adequate sugar levels may be produced but it will occur through dehydration while maturity of other components such as tannins and flavor and aroma compounds, do not fully develop.”
The range of yields that will produce quality is lower in Burgundy than Bordeaux because fruit quality drops off most dramatically with increases in yield for Pinot Noir as compared to Cabernet Sauvignon. Calera Winemaker, Josh Jensen observes, “There is especially with Pinot Noir an inverse relationship between yield and quality. If a wine is hurt by filtration, Pinot Noir will be hurt the most; if a given practice causes a wine to oxidize, Pinot Noir will oxidize the fastest; if a wine suffers from overcropping, Pinot Noir will suffer the most. Intensity and concentration decrease as yields go up. As you go from one ton/acre to two, the wine quality won’t dramatically change. But from two to three tons/acre, the wines start to get noticeably lighter and thinner.”
Low yields, when achieved through severe pruning and crop thinning do not necessarily guarantee quality.
Prats states, “It is quite obvious that low yield is necessary to achieve the highest quality, provided that low yield is achieved through low vigor and not through green harvesting or diseases which destroy the crop. The problem is not to control the yield but to control the vigor of the vine. That is the major quality factor.”