It is taken for granted that low yield and small berries make better wine. Now no one would suggest it is that simple, but often I feel as though winemakers/growers strive to reduce yields and berry size because that’s just what you do to improve quality. For anyone who has heard Mark Matthews speak, or taken one of his classes you will quickly learn that he has a penchant for challenging paradigms or at least clarifying the argument. In his vine physiology class he is quick to point out that lower yields typically produce bigger berries. And yes, to get the smallest berries minimal pruning, or high yields is the way to go. So what are we to make of this and what do we make of the extremely low yields in certain appellations of Europe?
The Matthews lab has been looking into the impacts of yield and water stress on berry physiology for some time now and recently put together an excellent summary clarifying the paradigm of yields and berry size. This diagram summarizes an accumulation of research predominantly performed on Cabernet Sauvignon in Oakville of the Napa Valley. What they discovered is intuitive, it is not low yields or small berries per se that drive quality, but how the berry/yield arrived at that size, or as they put it, its journey. For example, studies demonstrated that if the journey to low yields involved cluster thinning at veraison, there would be minimal if any sensory impact on the wine. In contrast, if the yield was reduced via water deficits (particularly pre-veraison as often occurs in Europe) then the wines become less veggie and more fruity, i.e. generally accepted to be better.
Many people may read this and say Of course, we’ve known this all along. Hmmm, well I’ll give you the benefit of the doubt but next time expresses it more succinctly and clearly. Most of what it seems people understood is that lower yields – regardless of the method – improved quality. It just doesn’t seem to be true, at least in Napa.