‘Comeback’ expected after big drop in ’08 grape crop

The damage has disappeared, but Mendocino County grape growers won’t soon forget last year’s frosts that caused their crop yield to plunge 25 percent from the year before.

“It was historic,” Devon Jones, executive director of the county Farm Bureau, recalled of the multiple spring nights of frost in 2008. What made it particularly destructive was a single April night when cold air blanketed the region and attacked hillside vines that normally escape damage.

Growers throughout the North Coast last year saw their yields drop because of frost and poor pollination. As a result, growers saw their income drop by $144 million.

But it was Mendocino County, where grapes and timber vie for the top agricultural category, that saw the biggest rate of decline.

The result is a highlight of the county’s new crop report. It shows tonnage dropped to 46,000 tons from 62,000 in 2007. Higher prices softened the blow, but the crop’s value still declined almost 18 percent to $62 million.

The pear crop also suffered a decline of 15 percent in tonnage, and its value fell 11 percent to $15 million. In comparison, logging produced a value at the mill totaling $67 million, down from nearly $75 million in 2007.

Grape growers will remember two particular aspects of the weather during spring 2008.

First was the abundance of frosty nights when vineyard workers had to stay out in the dark and cold to monitor and protect vines.

David Koball, vineyard director at Fetzer Vineyards and Bonterra Vineyards, said that this spring he had to cope with frost on five nights on vineyards between Hopland and Ukiah. But last year frost threatened the vines on 28 nights.

The second factor was a different and more serious type of frost that occurred April 20, said Tony Linegar, the county’s agricultural commissioner.

“That night the majority of damage to the grape crop and the pear crop occurred,” Linegar said. The overnight low hit 31 degrees in Ukiah.

Linegar said most frosts in Northern California occur on clear, dry nights when enough of the Earth’s warmth is lost that temperatures fall to critical levels. On these so-called radiant frosts, the coldest air typically collects in the lowest areas while the temperatures on hillsides are slightly warmer, usually enough so to avoid damage.

But on April 20 the region experienced an advective frost, which featured a large mass of cold air and a lack of warmth in the lower atmosphere.

Wind machines don’t do a good job protecting vines from such frost, Linegar said, because they rely on mixing layers of warmer and colder air. And Koball said in such a frost, the hillside vines can suffer considerable damage.

“It doesn’t matter if you’re on the valley floor or if you’re 2,000 feet above it,” he said.

Some hillside vines didn’t have wind machines or sprinklers to offer frost protection. And by April 20 some vineyard ponds had run dry because sprinklers had been on for many cold nights to keep the vines from freezing.

Fetzer and Bonterra’s vineyards saw their crop reduced 25 percent to 30 percent by frost and by poor pollination needed for the berries to set, Koball said. He oversees 1,150 acres for the two brands.

Now, a year later, Linegar said both the pear and grape crops are off to a good start this summer.

“We’re going to make a big comeback in 2009,” he said. “The pear crop is huge.”

In Sonoma County, the frost and other factors combined last year to reduce the crop by about 15 percent.

Pete Opatz, a viticulturist overseeing 5,000 acres of vineyards in Napa and Sonoma counties for Vino Farms, said this year he expects an average crop in the North Bay. But he said that may be a “blessing in disguise” because of the large inventory of wine already on hand.

“If we have a big crop,” Opatz said, “it will definitely bring down price.”

You can reach Staff Writer Robert Digitale at 521-5285 or robert.digitale

@pressdemocrat.com