05-Jan-10 11:40 | Eric Stafne

I’ll start with the bad news first — it is going to get very very cold.  The good news is that will all the cold weather we have had to this point our grapevines should be at or near their maximum cold hardiness level.  The maximum cold hardiness level is based mostly on genetics, but also is modified by outside factors such as previous year’s weather, crop load, disease and insect damage, etc.  So, essentially, management of the vines.  This is not easy to measure without some specific equipment.  If I had the equipment I could go out to the field today, collect buds, and put them through the testing procedure to have an idea of what is going on.  This is done in other states like Washington, NY, ND, and in Ontario, CA (that I know of).

Am I worried about the vinifera grapes?  Yes.  Depending on whom you believe, the temperature for Stillwater is projected to be as low as -1 F.  That could do significant damage to the less hardy vinifera (shiraz, merlot, zinfandel, etc.).  It may even affect mid-level vinifera (cab sauvignon, pinots).  We could even experience mid-season vine death once the crop gets heavy on the vine.  If all projections remain as they are now, I would not expect much damage on the more cold hardy cultivars (Riesling, Cab Franc), but injury is possible — mainly primary bud death and cordon dieback.  Some of the less cold hardy hybrids would also be vulnerable (Traminette, Chardonel, Chambourcin).

As I wrote about before, it would be good to check your bud damage level after the event or at least before you prune to assess proper pruning levels for next year.

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