Wine myths
Lower yields always mean better wine
“The lower the yield, the more concentrated and better the wine.”
Reducing an excessive crop on an unbalanced vine helps. Below that, cutting yield further does not reliably improve anything, and yield figures alone tell you almost nothing.
The full answer
The idea that matters is vine balance: the relationship between how much fruit a vine is carrying and how much leaf area it has to ripen it. An overcropped vine ripens its fruit poorly, and reducing the crop fixes that.
Once the vine is in balance, the relationship stops. Further reduction has repeatedly failed to produce measurable improvement in trials, and can push a vine into excessive vigour that causes its own problems.
A yield number in isolation is close to meaningless. The same tonnage per hectare means completely different things at different vine densities, and a hectare planted at 10,000 vines is asking far less of each vine than one at 2,000.
Variety, rootstock, water availability, soil fertility and target style all move the appropriate number. There is no single figure that is correct across regions, and appellation yield caps are policy instruments as much as quality ones.
Grossly overcropped vines really do make dilute wine, and yield caps really did raise the floor in regions that had none.
Why the belief persists
It is the one production number that appellations publish, so it became the number everybody argues about.
A relationship that has been measured across real samples — a correlation between growing-season temperature and harvest sugar, say — without a single demonstrated mechanism covering the whole path from cause to effect.
What would settle it: A larger or better-controlled study finding no association.
Sources
Sources consulted
- UC Davis Department of Viticulture and Enology — University of California, Davis
- International Organisation of Vine and Wine (OIV) — OIV
- WSET educational materials and the Systematic Approach to Tasting — Wine & Spirit Education Trust