April 06, 2015 – Dan Berger
John Williams, the visionary Frog’s Leap Winery owner from Rutherford in the Napa Valley, was the most logical go-to person when an idle comment from a shop owner suggested that the wine industry could face water-shortage problems very soon.
Williams, ever his contentious self on the topic of vine irrigation, is a walking encyclopedia on the subject of water use in vineyards. But his opening line when I called him last week to speak of water use in vineyards, though typical of his philosophy, was still a bit of a shock:
“We (in Napa) are drawing 1.2 billion gallons of water and putting it on vines that don’t really need it,” he said.
It’s important to know that Frog’s Leap is one of the most vocal advocates of organic farming, and Williams is a firm believer in dry-farming of vines to make better wines.
Williams’ basic story here is that the best wines are made from vines with deep roots and that by irrigating as routinely as they do, the majority of Napa growers are feeding the vine a drug (water) — and there is no methadone solution.
“The entire valley was dry-farmed for 100 years until 1976 when the first drip irrigation systems were installed,” Williams said. “When the vines have easy access to water, they do not have to push their roots down very far.”
He says that shallow root systems led to fruit that’s lacking in flavors until later in the season. And a result of that is that growers pick later than they would need to if they were set up to be dry-farmed. As it is today, the broad use of irrigation leads to alcohol levels that are higher than they should be, he said.
“Look, vines aren’t stupid.” he said. “If water is easily available, they won’t have deep roots.” He says wine quality is related to root depth, and the lower the roots are, the more likely the vine is to produce better quality at earlier dates.
He said vines are relatively savvy plants and “plant physiology tells us that the brain of a plant is designed to” employ certain strategies for propagation of the species. “If you mess with the information system, the plant doesn’t know when to stop growing and put its energy into (grape) flavor development.”
The target of the grower, he said, “is to get the vine to make its own decisions, to smartly employ all that’s in the soil. The plant should be more in control over its own destiny.
“Dry framing is not just ‘not irrigating,’ it is a real skill, and an arduous process, and it’s very complicated.”
He said that once a vineyard is established with an irrigation system, it’s difficult to wean the plants off the drug. “You can’t just turn the water off.”
He said Napa Valley’s water use, for irrigation only, which he estimates is at least a billion gallons annually, comes from a quick calculation he made from a UC Davis report that estimates water needs for an acre of fruit — about 100 gallons of water per vine.