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                       Quality Made Wines with fruit exclusively from the Northern Plains!  

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Measuring Spring: Dreading frost!

Posted on April 15, 2012 at 10:30 AM

April 15 (OMG it's Tax Day!)

But vineyard owners in the  midwest haven't been thinking about taxes.  They've been consumed with information about frost.  For many, this has been the worst year on record.  Let me provide a bit of background on how we measure and what we do in the spring.

MEASUREMENT

  • PHENOLOGY:Vineyardists, like many nature watchers, use a concept called "phenology" which is the study, notation and attention paid to when things happen.  Generally, grapes bud out in Miles City around Mid-May.  This year, it appears likely to happen around April 20th, more than three weeks early.  Generally, our flowering crabs blossom about May 15th as well.  This year they are already in blossom.  Everything across the midwest has been about a month or more early.
  • GROWING DEGREE DAYS (GDD):  This is a measurement tool that sums up the average heat above 50° F. throughout the growing year.  50° F because that's approximately the temperature above which grape tissue actually does something and doesn't just sit there.  In Miles City, we get about 2700 GDD each year.  Generally about this time, we've only had 15-20 GDD.  But this year we're already up to 85.
  • STAGES OF GROWTH:  Why do GDD matter?  Well, with most hybrid grape varieties, budbreak happens at about 100 GDD, and up until just before budbreak, the vines can take a pretty good freeze.  At budbreak and after, just a couple degrees below freezing can be deadly (literally!)

WHY THIS MATTERS: 

  • LATE FROSTS:  With spring so early this year, we are all at risk for late frosts that can kill the buds (but not the plant.) It just means that we might have to do all the work of pruning, training, etc. and get nothing in return this year. SO FAR with 85 GDD, we have not reached budbreak, so the frosts haven't harmed us.  But our last hard frost average is close to the middle of May, so we might lose our crop in the next four weeks even though things look good now.
  • HOW ARE OTHERS DOING?  GDD in Minnesota, Wisconsin, Iowa, Nebraska, Michigan is well up toward or above 200.  That means their buds have burst, and they have little canes between 1-3 inches long.  And they are having hard frosts in some of those locations. 
  • HOW BAD CAN IT GET?  I just read last night that it appears that up to 90% of the Welch's controlled vineyards in Michigan might be a total loss this year. Iowa reports that they believe they might be somewhere between 10-90% damaged, depending on location and variety.  Damage is being reported everywhere in the frost zone  that has had such a warm spring.

WHAT CAN BE DONE?

  • HEAT:  A number of vineyards use huge propane jets (like a salamander heater only 10 times as big) and drive up and down the rows trying to heat the air.  Some hire expensive helicopters to hover over their vineyards in a moving pattern, to push warmer air above down to the ground.  Others light smudge fires.
  • OVERHEAD SPRINKLING:  Some vineyards are set up to spray water on their vines overhead, coating the leaves, buds, twigs, everything.  The science of this is that as water freezes, it gives off heat, and keeps the tissue beneath the ice just above freezing.  But it's tricky to do, and most of us don't have the equipment or enough water to do this job.
  • SPRAYING WITH CHEMICALS: Some vineyards have tried spraying with certain fertilzers/chemicals that are supposed to be cryo-protectants.  There IS some evidence that this might work, but only for a few degrees.  You might survive at 30° F, but not at 22° F if the buds have opened.
  • PRAY!
  • DIVERSIFY.  Here at Tongue River Vineyard & WInery, we had a total crop failure two years ago due to frost at the other end of the year:  Early hard fall frosts can severely weaken the above-ground portion of  vines if they haven't had time to harden off and get ready for winter.  We got caught due to frosts on my wife's birthday (Oct 10th) and a couple more days in 2009, which basically killed everything above ground.  We spent all of the summer of 2010 rebuilding the trunks, cordons and canes for the 2011 harvest and it paid off.

But many vineyard/winery operations have ONLY grapes, and that's where the real hurt comes in our unpredictable climate.  We did pretty well our opening year because of all of our fruit wines, and we continue to increase and expand our offerings there.  We will pick our first haskaps and Canadian cherries this year.  We've significantly increased our holdings in apples, pears, black currants, sand cherries, raspberries, elderberries and rhubarb.  And our two highest selling wines continue to be rhubarb and Foxy Lady (our apple/currant blend.)

Anyone engaged in any farming venture needs to be able to shrug one's shoulders and say, "oh well, next year."  Or as our friends in Broadus, just south of us like to say even more cynically, "This is year after next country!"

Pray for frost free weather for the rest of spring.  Please.  Double, triple infinite please!!

Categories: IN THE VINEYARD