Time for a drink? Dry winter has grape growers watching the sky

January 15, 2018
011718 FD wine art vines

This winter has been neither extremely cold nor extremely wet, and only the first pleases grape growers. Grape vines are being freeze-dried as they lose moisture during the winter months.

If you’ve taken a stroll across your lawn recently, you know how parched things are.

January normally is a dry month for Colorado but until this past week’s smatter of moisture this winter has been especially dry. Certainly not normal, even for the high desert, and home owners in western Colorado have been urged to water trees and landscaping to prevent future damage.

But what do you do when your “landscaping” involves acres of grape vines?

The Grand Valley is no stranger to dealing with cold damage to grape vines. Hard winters (including the devastating winter of 2002/03 and most-recently in 2014) are among the challenges facing grape growers.

But this year, with daytime temperatures still climbing into the high 30s to mid- 40s (at this writing it is 48 degrees in Grand Junction) with nary a lick of snow on the ground, brings a new set of challenges.

Grape vines store a sort of anti-freeze in the form of stored sugars from last year’s photosynthesis but deep cold still can damage or kill buds, trunks and canes.

Also, a long, dry winter can desiccate older plants and kill young ones.

“We’re basically freeze-drying the vine tissue,” explained Horst Caspari, state

011718 FD Wine dry vines 2

Except for the ground surface being dry, there’s nothing wrong with this vine a good snowstorm won’t fix.

viticulturist at Colorado State University’s Orchard Mesa Research Center. “Over the last three months we’ve had virtually no significant moisture, so it’s definitely a concern.”

While night-time temperatures aren’t far the long-term average, daytime temperature are averaging about 12 degrees above normal. Caspari said.

As any fruit grower can attest, winter damage often doesn’t show itself until spring, when warmer temperatures start the regrowth process.

“It concerns me, that’s for sure,” said grape grower Kaibab Sauvage, owner of Colorado Vineyard Specialists LLC in Palisade. “Vines can be damaged if they’re dry and they damage more easily at higher temperatures if they’re dry.”

A brochure from the University of California-Davis tells grape growers to maintain some ground moisture during dry winters in order to supply needed moisture for even bud break and flowering once vines break their winter dormancy.

Most vineyards in western Colorado get a heavy watering just prior to the irrigation canals being shut off, which usually is adequate for surviving the winter and getting a head-start for the following spring.

“We try to get the soil profile really full of water in the last week before we lose the (irrigation) water,” said Nancy Janes of Whitewater Hill Vineyards and Winery. “Around the last week of October, after we get things hardened off for the winter, we’ll blast it with water and hope it makes it pretty well through the year.”

The soil moisture also acts as insulation by filling the gaps that occur in dry soil.

“Most vines send their roots really deep, so they find water even when it’s not obvious,” Sauvage noted. “But young plants and shallow-rooted plants may be struggling right now.”

Snow also helps insulate the ground, particularly the upper few inches.

“Right now, at 6 inches down,  the soil isn’t frozen and it rarely does in our part of the state,” Caspari said. “In wet soil, water is a good insulator but when you’ve had a dry period the frost penetrates much deeper and roots get damaged much easier than do buds.”

“If there was no rain or snow in the forecast, I’d rush out and water today,” he said.

Grower Galen Wallace, who has weathered some 30 winters providing grapes to Colorado’s wine industry, recently said he will be more concerned if the present conditions continue into March.

“So far, I’m not too worried,” he said. “Now, if it stays dry like this and we get some cold weather early in March, even something that’s not unusual, say lower 20s or even in the teens, it could impact our crops.”

Nancy Janes shared that sentiment, saying the mild winter so far has been pretty worry free.

“Most of our challenges seem to come from cold temperatures,” she said. “We may another month of this and then by mid-February or later is when everything starts to change.”

The damage starts to show when the vines break dormancy, Wallace said. “Growers could see a reduction in vigor, so they have to be aware of what’s happening in their vineyards.”

He advised growers to begin irrigating as soon as water is available.

“If the canals are filled on Wednesday, growers should have water running on Friday,” he said. “What worries me more right now is the lack of snow and what it might mean for late-season water.”

Sauvage and other growers in the valley have very few options when it to getting water to his vines.

“We can only hope there are some storms heading our way,” he said.


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