On an overcast February afternoon, winemaker Bennett Price walked away from a barrel of wine he was readying to bottle and headed outside, to a fence near his DeBeque Canyon Winery where clusters of very dry grapes were shifting nervously in the breeze.
“These are Pinot Noir,” he said, reaching under the bird-proof netting drawn over the vines. “They were pretty good grapes, too, but they came on real early last spring, too early really to do anything with.”
On the third consecutive day of 60-degree plus highs, in what’s suddenly behaving as if it were the northern extension of the Colorado Banana Belt, one can be forgiven if the weather has you thinking more of mid-spring rather than mid-winter. While the sides of nearby mountains still wear thick blankets of snow, there hasn’t been any snow, or any moisture of any kind, in the lower valleys for several weeks.
Instead, here at 4,200 feet, plenty high enough for winter to return for another month or two, birds are building nests, golfers are swinging away and winter-dormant lawns are starting to green.
“I think we’re going to have an early bud break,” Price said. The unseasonal temperatures “warm up the soil too much and that stimulates the roots to start pushing.”
The temperatures, while warmer than normal – unless this is the new normal – still haven’t been consistently high enough to break the vines’ winter dormancy. It takes 50 degrees to see the return of spring, said state viticulturist Horst Caspari.
“And that’s on a 24-hour cycle, not just a quick jump up and then back to below freezing,” he said. “We’re still getting enough diurnal variation that nothing’s broken yet.”
Yet Bennet Price isn’t convinced after hearing a weather forecast calling for cooler temperatures followed by more warm days.
“We were up to 60-something yesterday and our low was 46 or something like that and today it’s back up there again,” he said. If the vines do respond to the warmth, “hopefully we won’t go back down to the low 20s or teens because you can start damaging the canes and trunks because the sap’s coming up.”
Tree-fruit growers are extremely wary of such mid-February warm spells because their trees are close enough to bud break that prolonged mild weather can bring early and unwanted development. Climate change hasn’t yet brought Western Colorado to where a heavy spring frost is out of the question.
Grapes, however, come on several weeks later than cherries, peaches and apples, which gives a bit of leeway and enough time for the weather to back to cold.
“But he’s right, the ground is being warmed up,” agreed grape grower Neil Guard at Avant Winery on East Orchard Mesa. “And look, it’s dry, there’s no snow at all. Which means if it stays warm, the vines are going to need water and we can’t get any irrigation water until April 1.”
Should the vines suffer freeze injuries, they then are susceptible to a bacterial infection called crown gall, which can eventually kill the vine.
Crown gall, caused by a bacterium that lives in the soil, also can result from mechanical injuries caused by normal vineyard maintenance such as pruning, grafting and training vines.
“I’m working in some vineyards and I have to go through and mark the vines with crown gall so they don’t prune that vine,” Price said. “You don’t want to prune that vine because if you prune it and then go to the next vine, you’re going to pass that bacterium to the next vine.”
He said the only way to treat crown gall is to pull and burn the vine and replant.
“It’s just another thing to think about if you’re planning on owning a vineyard,” Guard said, with a laugh.
– Photos, story by Dave Buchanan