Grapes are a unique agricultural product. While more than half go toward the production of wine, they are also grown to be dried into raisins or eaten fresh. Grapes command more return per acre than almost any other plant, and in 2018, a single hectare of grand cru vineyard in Burgundy cost over seven million dollars on average. Further, unlike many crops that are planted each growing season, vineyards are a long-term investment—they require several years to become established and are designed to survive for decades.
Unlike many commodity plants, the profitability of wine grapes is driven by quality, which includes the grape’s ability to convey a unique sense of place. While other agricultural crops look to new varieties for flavor improvement, disease resistance, and adaptations to climate, most wine producers rely on a small number of established cultivars. Site selection and vineyard practices, however, are critical, since improvement is achieved through management of the vine’s environment.
Grapes were one of the first fruits to be domesticated by humans. In ancient times, they were prized for their high levels of sugar, a source of both nutrition and novelty. Most of the grape varieties used in wine production belong to a single species, Vitis vinifera, which was first domesticated from wild grapevines, called Vitis vinifera subsp. sylvestris (or Vitis sylvestris), at least 7,000 years ago in the land between the Black, Caspian, and Mediterranean Seas. As nomadic people settled into an agrarian lifestyle, they carried grapevines south to Mesopotamia. Domestic vinifera grapes were spread from the Fertile Crescent throughout the Mediterranean and Europe, driven by the westward migration of
Thanks for another great article and the accompanying podcast Jennifer. I wish I’d had this when studying for my Diploma. I wanted to ask you about two things you mentioned in the article and the podcast. The first was about the number of clusters produced per shoot and how this might change as a plant grows old. You said that most shoots contain between one and three clusters, with two being most common. As a vine gets older, we’re told that yields typically decrease, and I wanted to ask if this is because the plant starts producing fewer clusters per shoot, fewer berries per cluster, or smaller berries (resulting in a greater skin-to-pulp ratio), or perhaps a combination of all three? Also, if old vines do in fact produce fewer clusters per shoot, is it possible that a shoot from an old vine may not produce any clusters at all in a given year due to age (rather than weather events, disease, etc)? My second question was about soil pH. Is there any relation between soil pH and the pH in the final wine? You mentioned that slate soils in the Mosel can be fairly acidic with a pH below 6, but perhaps the high acid levels in Mosel Rieslings have little to do with soil pH and much more to do with the cool continental climate and acid retention of the variety itself? Thanks again!
Hi Nygil, thanks for your wonderful questions and I apologize for my delay in getting back to you, but I wanted to check-in with a few other people to try and get the best answer to your question.
The question about old vines is a complicated one. First, I think it's important to realize that "old vines" is not well defined, but it's helpful to recognize that there are young vines, what I'll call "mature vines" or middle age vines, and "old vines". I think of young vines being less than 7 or 10 years old, but old vines are harder to characterize. The Barossa Old Vine Charter includes vines over 35 years. These things aren't well-defined, and how quickly vines mature depends on environment. Some people say that vines mature more quickly in a warmer climate.
Then, to answer your question, the idea that yields decrease with vine age is based on observation, which might be a bit faulty. Dylan Grigg did a comprehensive study of old vines in Australia. He looked at 5 sites over 3 years with nearly identical management and vineyard design between old and young vines. This study actually found that old vines there tend to have slightly higher yields driven by having more berries per bunch, though these results were inconsistent. This makes sense since old vines have thicker trunks and more permanent wood, and based on the concept of vine balance, this would give them greater capacity to produce more fruit. He did compare the number of clusters, berries, and berry mass, and the results were inconsistent across years and sites.
That said, producers have certainly observed lower yields in older vines (me included). There are a number of reasons related to age that yields might decrease, including vine health and management. For example, old vines may be missing spur positions (from trunk diseases or pruning scars), so they may have less clusters, or they may receive less irrigation since they often tolerate water stress better, and as a
Thanks so much Jennifer, I hadn't kept all of those relevant factors in mind regarding yields, but the points you brought up all make sense. It's always sobering to be reminded that things are never black and white, as much as we may want to paint them that way in the classroom for students sometimes.