The vines are asleep. Dormancy is a very interesting phenomenon. What happens when a plant enters dormancy and moves towards deep dormancy is that individual cells shed water, which is deposited in the spaces between the individual cell’sintercellular spaces. This watermigrates through the cell membrane when temperatures drop and day length shortens. The reduction of water from the cytoplasm within the cell causes the level of salinity (or salt concentration,) to rise, providing a kind of internal “anti-freeze.” That is to say, the higher the level of salinity, the less likely the cell itself will freeze.
Vitus vinifera varieties like cabernet sauvignon, merlot, chardonnay, pinot noir and syrah are quick to de-acclimatize when the temperature changes. When we have episodes of three to five days when the temperature reaches 60 degrees in January, (as we seem to have every January,) these vitis vinifera varieties think it is springtime and begin to de-acclimatize, that is, the water parked in the intercellular spaces starts to migrate back inside the cells. When
temperatures drop to normal after a warm episode and temperatures dip below freezing to twenty degrees or the teens, the individual cells try to expel the water that they have just taken in.As the water is being expelled, ice crystals sometimes form, creating “little daggers,” which pierce the cell membrane, irreparably damaging the cell. In fact, in many cases the entire contents of the cell may leak through the hole created by the “ice daggers,”resulting in cell death. This damage can occur in a bud, a shoot or in severe circumstances, to the trunk of the vine.
People ask me why we grow hybrid grapes instead of vitis vinifera, and the answer lies in this January phenomenon. The hybrids we grow ~ Chardonel, Traminette, Vignoles and Chambourcin ~ are very slow to de-acclimatize. What I mean is during warm temperature episodes, our vines are very slow to allow water back in after dormancy has been reached. This is what allows our hybrid grapes to survive in the face of repeated warming & cooling episodes that occur here in Missouri in January and early February.
Last week our Winemaker Mark Baehmannbrought a glass of the new Dry Rosé 2013 vintage to my office. Since we are running low on wine because of low production in 2012 due to frost and increased demand throughout 2013, we’ve decided to bottle the new wines in February of 2014. The first of these will be our new Rosé, which will soon be ready to bottle. The first tastes that I had last week tell me we will have one of the best if not the best rosé that we’ve ever bottled. The color this year is a little deeper. Last week, I had a guest who is an enologist from Greece and Italy who also has wide knowledge of French wines. I gave her a taste of the new rosé; she loved it and thought that it resembled wines that she had had from the Tavel region of southeast France. Many people feel that the best dryrosés in the world come Tavel, located on the right bank of the Rhône, west of Avignon. Imagine my smile upon hearing her say this.
Hank & Jackie Johnson
Thank you all for joining us for ourAutumn Annual Winemaker’s Dinner in November ~ what a terrific event it was! We hope that you have a very joyful and healthy holiday season, and we look forward to seeing you very soon!