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36 W i n e s & V i n e s M AY 2 0 1 4 W I N E M A K I N G crop demand) and balance is more impor- tant. A ton per acre on a healthy, mature vineyard is a low crop load, but on a first- year vineyard it is an overcrop. It also depends on the climate, sunshine, etc. Low yields (or crop load) often would be expected to produce more concentra- tion, though recent research at Gallo and others on crop-load effects has shown that chemical and sensory analyses of aroma, flavors and mouthfeel respond differently to crop level, depending on variety. Many varieties did have the best overall "qual- ity" with low to moderate crops, then de- clined with heavy crops. Cabernet-types had poor quality with low crop, probably due to excess vigor with low crop. Char- donnay showed almost no response to crop. Pinot Noir had normal response of aromas and flavors, but the mouthfeel re- quired low crops to be best. So the answer is "it depends," because it really does! Zufferey: Generally limited or relatively low yields lead to good berry maturity, but each variety has an optimum yield for the best variety and terroir expression. For example, if you maintain very low yields with the cultivar Chasselas, you lose too much berry acidity and the wine presents a disequilibrium. I prefer to speak about a good leaf/fruit ratio (sunlight exposed leaf area/kilogram fruit production) that is necessary to obtain a good grape maturity and variety/terroir expression. Depending on the climate conditions, this leaf/ fruit ratio should be around 1 m 2 exposed leaf area/kilogram fruit to obtain a good berry maturity. For some late-ripening varieties, this ratio has to be higher (1.5 m 2 /Kg). Van Leeuwen: Although there is obviously a limit in yield beyond which quality decreases, this limit is not universal. It's much better to speak in terms of exposed leaf area/fruit weight ratio (ELA/FW) instead of absolute yield. Ideally, ELA/FW should be above 1.5m 2 /kg. The following rules apply: • Yield is more of an issue for red wines than white wines • The relation of yield to quality depends on vine water status. If vines are water stressed, high yield will severely impact quality because photosynthesis is limited. If water stress is moderate, vines can produce high quality with moderately high yields (up to 10 tons per hectare). Choné: The lowest yield does not always produce the best grapes and wines. Anyway, balanced yield is key. It is important to consider the yield per vine and not always the yield per surface area unit. Keller: This is a question of supply and demand (i.e. balance) and has nothing to do with terroir. The correlation between yield and character is tenuous at best. Low yields usually hasten grape development and ripening, which is beneficial for fruit quality in cool years but detrimental in warm years.…For red wines, berry size (i.e. skin/juice ratio for color and skin tannins, etc.) rather than yield may be important, but this may not be true for many white wines. Keeping yields (too) low sometimes results in the vines compensating by producing bigger berries and by growing more vigorously (they have to do something with the sugar their leaves produce), which then requires more canopy management and other costly practices. McGourty: I like what Dan Berger says: "If lower yields make the best wine, then you should have superior results when there is no fruit in the vineyard!" Absurd, of course. Good wine can be made from fairly large yields if the vines are in balance. In general, balanced vines produce the best wine: 5 Your success is our prioritY Think Grandly. Since 1939 707.836.9742 www.cantoncooperage.com