Dry winter triggers early irrigation start

Dry winter triggers early irrigation start

The last thing Central Coast wine grape growers wanted to do this year was to start irrigating in February, but many did in a year that producers are calling one of the worst droughts ever.

Central Coast wine grape grower John Salisbury did something he thought he’d never do so early in the year – he began running water through his drip system in late February.

“It’s unheard of to start irrigating this soon here,” says the sixth-generation California farmer who, with his family, grows wine grapes in the Avila Valley of San Luis Obispo County, south of San Luis Obispo. “Since the first of this year, we’ve had one of our worst droughts ever.”

Here, close to the coast, but shielded from wind by the surrounding hills, summer weather features cool nights, foggy early mornings and daytime temperatures in the mid-70s. Conditions ideal for the family’s 35 acres of Albariño, Chardonnay, Pinot Grigio, Pinot Noir, Merlot and Syrah.

Normally, Salisbury doesn’t start his first irrigation until April or May. However, by mid-April this year, he had already irrigated his vineyards three times.

He’s even been irrigating a five-acre block of grapes next to a creek, where he can normally dry-farm, except for several irrigations at full fruit set and then after harvest for the root flush that occurs.

The rainy season started out with good amounts of precipitation in November and December. It appeared that the valley would receive at least the average 24 inches or so of rain that falls before the rainy season ends in early spring. However, rainfall has totaled only 8 inches so far.

“There’s no rain in the forecast, either, but we’re coping with it,” he adds.


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This comes as continued development in this and surrounding areas of the county puts even more pressure on the region’s aquifers.

Still, the late March bud break on the Pinot Noir vines, followed next by Chardonnay and Pinot Grigio, was pretty much on schedule, Salisbury notes.

The warm weather has kept the newly-developing vines pushing out.

“Shoot growth has been great,” Salisbury says. “The vines are happy, and we’re already seeing grape clusters beginning to form in the Pinot Noir.

Salisbury Vineyards also includes 10 acres of grapes west of Paso Robles, where the much warmer climate favors the family’s Cabernet Sauvignon and Zinfandel. Often, rainfall provides much of the moisture on the west side of the freeway to support the crop there through the season. Here, too, the dry winter forced an early start of irrigation this year.

Salisbury provides his vines most of their nitrogen budget in the fall, usually UN32 or a recommended blend. In May, he uses petiole analysis to determine any additional nitrogen needs. Usually, none is required then.

“All of us here are very conscious of the need to keep nitrates out of the water,” he says. “We don’t want to put on any more nitrogen than needed.”

Dry weather has minimized any pressure from powdery mildew, Salisbury reports. He’s been spraying his vines with his customary 2 percent mineral oil treatment to prevent any mildew outbreaks. This treatment also smothers any aphids and mites which may threaten the crop. Salisbury times his treatments using the Powdery Mildew Index, developed by the University of California, and personal observations. When needed, he includes a fungicide with the oil to suppress higher spore numbers.

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