Wind machines help fight frost

Grand Valley grapes are starting to show promise of this year’s crop after surviving a late-April freeze. Many vineyards in the valley still are recovering from the Dec., 2009, freeze that killed thousands of vines.

The spring storm blowing through the Grand Valley early this week may keep grape growers out of the vineyards, but at least it won’t keep them awake.

Consider yourself lucky if a week ago you woke up late to find snow on the lilacs.

Sleeping in, lingering over a cup of coffee and marveling at the beauty of winter’s final fling wasn’t an option for most of the valley’s fruit growers.

Most of the orchardists and grape growers were up well before dawn several times in late April after record low temperatures set off frost alarms.

That low mark of 24 degrees on April 30 set a record for the date, eclipsing the previous mark of 27 from 1909.

Most growers across the valley reported little damage, even though it doesn’t take much to freeze a grape bud no bigger than a pencil eraser (you do remember pencil erasers, don’t you?).

It was just as cold or colder along the North Fork Valley, where temperatures last Thursday morning hovered in the low 20s.

But most Delta County grapes are a week or so behind the Grand Valley crop, which means they had not lost the cold-hardiness needed to resist these late-season frosts.

Thirty years of weather data say April 23 is when the last frost hits the valley, but Horst Caspari, state viticulturist at the Western Colorado Research Station on Orchard Mesa, said this is the fourth consecutive year that a frost has hit after that date.

“It was the second of May in 2008, last year and this year and April 27 in 2009,” he said. “It was definitely colder on (April 30) than (April 29). My cabernet franc grapes are fried.”

The roar of wind machines broke the early morning silence on several days, but these 50-foot fans can’t promise a saved crop.

Caspari said the machines, designed to mix cold air along the ground with warmer air above, usually split the difference in the two temperatures.

“The rule of thumb is a gain of only half the difference,” he said. “But if it’s 5 degrees warmer at 50 feet and my (ground-level) temperature is 28, that 2 1/2 degrees can make a difference.”

The machines also move enough air to keep cold air from settling in the low spots, and there are a number of vineyards around the valley that have a trouble spot or two.

“Some of the spots are noticeably colder,” said Caspari, adding that cold spots might not be geographic but rather caused by bushes or building blocking the natural flow of cold air.

“I can find vineyards where you’ll see 11–12 degrees temperature change from one end to the other,” he said.

One last note on late-spring frosts: Forget the idea that cold-aided “natural thinning” is good for orchards.

Sure, most fruit growers end up heavily thinning their crop but they do it evenly over the tree.

When nature thins the crop, she does it only on the bottom, where the cold air settles.

“Yeah, natural thinning tends to be at the bottom, not at the top,” agreed Caspari. “So if you lost 30 percent of your buds, they aren’t distributed evenly.”

He explained growers still have to thin at the top to balance the crop load.

“Growers may thin a little less heavily at the top than normal but it’s still a yield loss,” he said. “You might think that now there’s less fruit to come off (during thinning) but you can’t fully compensate for the frost damage loss.”

ABBEY WINERY SEEKS ARTISTS: The Winery at Holy Cross Abbey in Cañon City is looking for an artist to feature for the winery’s 10th annual Jubilee Harvest Fest 2011 in September.

According to Abbey spokesperson Sally Davidson, the selected artwork will be used on wine labels, posters, invitations and other media promoting the harvest festival.

Additionally, reproductions will be sold throughout the year in the tasting room.

Artwork must be delivered to the winery tasting room at by June 27 with judging set for July 1.

Information: Sally Davidson, 719-276-5191 or email .(JavaScript must be enabled to view this email address).

DRINK LOCAL: is coming to Colorado in 2012 and you are invited.

Drink Local Wine was created by wine writers Jeff Siegel ( and Dave McIntyre ( as a way to ensure “regional wine gets the respect it deserves,” as they say on, and to focus on wines that aren’t from California, Washington or Oregon.

The group recently wrapped up its annual conference, this year it was in Missouri with earlier conferences in Texas and Virginia, and next is Colorado and its 100-plus wineries.

There still is a lot to get settled but start with and particularly the “How you can help” link on the right side.

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Email .(JavaScript must be enabled to view this email address).


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