March Warm Spell “Dark Cloud” for Midwest Grape Growers
Spring-like temperatures so soon in the year may be swell for joggers, but vineyard managers aren’t so thrilled.
With June level temperatures forecast for the Midwest during the week of March 12, there are widespread concerns about early bud break.
Next week’s forecast for St. Louis predicts highs from the upper 60s to the high 70s, and even the Twin Cities area expects a spike into the 60s for daily highs. Evening temperatures aren’t cooling down enough to give the vines a break. If a hard frost follows the warm spell, 2013 yields could be adversely effected.
In the Minnesota Grape Growers Association’s online chatroom, Mark Hart of Mt. Ashwaby Vineyard & Orchard in Bayfield, Wis., in Northern Wisconsin, dubbed the upcoming warm spell ‘a big dark cloud.”
‘This is very similar to what occurred in 2007, and that led to what is known as the Easter Freeze of 2007, which caused widespread damage to grapevines and the 2007 fruit crop all over the Midwest,” says Hart in an interview.
Soil temperatures of 60 degrees and above can cause an early bud break. Bill Shoemaker, who runs the University of Illinois Extension vineyard in St. Charles, Ill., suggests leaving longer spurs on the vines, to result in eight to ten buds, instead of the typical two or three, as a method for delaying bud break.
Some vineyards have already completed pruning — well ahead of schedule. Alarmed by ‘too many scary warm days,” David Ponce, owner of Monte Allegre Vineyard in Southern Illinois, started pruning on February 5 and wrapped up by March 1.
‘We have another two weeks of sitting on our hands,” says Ponce. ‘If we can clear April 1 without significant swelling we’ll be out of the woods. Once we start getting nights in the 60s that’s bad news.”
Editors Note: Please see John Marshall’s “Frost Protection for the Small Grower” in the Viticulture section on the home page of Midwest Wine Press. An article in the February 29th “Ohio Grape-Wine Electronic Newsletter” discusses using soybean oil to delay bud break. Visit http://www.oardc.ohio-state.edu/grapeweb/ for more information.