Marechal foch red grapes at Wollersheim Winery in Prairie du Sac, Wis. Vineyard manager Bruce Reeve says they're at a very vulnerable stage in their development and they're concerned about the cold overnight temperatures. Photographed Thursday afternoon, April 5, 2012. M.P. King-Wisconsin State Journal

When frost was predicted to cover the area last week, Wollersheim Winery's Julie Coquard predicted that 10 percent of the vineyard's buds would be lost.

Coquard now believes her prediction was too optimistic.

"We definitely lost more than that," said Coquard, a co-owner of the Prairie du Sac winery. "We're not quite sure how much because different parcels of our vineyard are at different stages. And then it doesn't show up for a few days. But it was pretty tough these last few days."

Coquard's husband, Philippe, hasn't slept much over the past week. He's been running large fans and towing a "frost dragon," which spews hot air over the grape plants, through the vineyards in the early morning hours. But the frost was relentless.

"With each progressive night, everything is weakened from the previous time," she said.

Coquard said this is the worst spring cold snap she has encountered at Wollersheim. "We've had a few bad ones, but usually things aren't this far along, so there's a chance for the vine to make it up," she added.

Fortunately, just the buds are damaged. "Depending on the stage of the bud, there's a chance that a secondary bud could still have one cluster of grapes. Usually we have three clusters per bud," she said. "So it won't be a total loss. Even if we lose 50 percent of the buds, it won't be 50 percent of the crop."

About 25 miles south near Barneveld, Sarah Botham of Botham Vineyards & Winery said her business has been luckier. First, she said they've had the benefit of a constant breeze that stalls frost's effectiveness. Second, their vines aren't as far along as Wollersheim's.

"We're not nearly as leafed out as Wollersheim," she said. "We maybe have 10 percent of our buds broken and leafed out. We have one whole field where nothing is open at all."

In Gays Mills, Faye Welsh, the owner of the Turkey Ridge apple orchard, is thankful that frost hasn't damaged any of her apple trees, which are in full blossom. "I waited and waited and I never saw it dip below 32," she said.

Welsh added that all of Gays Mills' apple orchards are in full blossom right now. "It's absolutely beautiful," she said.

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