Greetings from Sunny California
www.farella.com
What's with the weather? I can't remember the last real rain and ski season is supposed to be in full swing. It's been the iciest winter that I can remember, having grown up in the general vicinity. This photo is from, normally, a waterfall above our winery. This year it is an ice sculpture. It's quite beautiful but a little disturbing. We've had ice and dry winters over the years, but this seems a little unusual.
I have fielded many questions on the effects on the vines of little rain and the icy temps but, for now, it is of no consequence in the vineyard except that you can take tractors out in the vineyard, if necessary, and get some of the spring chores done. It's probably a good idea, in fact, since the next thing we know there will be some deluges around the corner and another late, wet spring.
Wine grapevines, specifically Vitus vinifera, can tolerate temperatures down to 10 degrees Fahrenheit without any damage during the dormant season. I should mention that this includes most table and raisin grape varieties. Back East, some of the other Vitus species (think Welch's grape juice) and hybrids can tolerate down to -10 degrees Fahrenheit so they are much more winter hardy. Unfortunately, these varietals are not known to make world-class wines. "Winter kill" is the farming term for an unfortunate combination of species and location. Places like eastern Washington are a great deal more susceptible to this danger and there may be some stories of loss after the icy winter there.
On the subject of drought, again, it's not really a factor at this time but we do need the aquifer restored for the late summer irrigation season seemingly so far away. So many changes are in store for the rest of the winter but the daffodils are starting to bloom, the crocuses are popping out and I saw some new poison oak leaves today. Spring is around the corner and the vineyards will be thriving with activity to get the vines on course for another growing season -- just when we thought we could take it a little bit easy. I still feel a touch of those post-crush blues but nothing a real ski season can't remedy. Hmm. Maybe there's a problem here?
Cheers,
Tom
Greetings Tom! It has been abnormally cold of late. Your ice sculpture is really quite amazing, thank godness your vines can sustain the weather. One question, what do you think would happen to your vines if it dropped below 10 degrees F?
Posted by: Ryan F | January 23, 2007 at 04:36 PM
Hey Ryan old buddy
The question about "winter kill" is, fortunately, something we don't have to deal with. At temps under 10, the vine tissue dies back depending on how long and how cold. They can bounce back if there's live tissue (don't get me started on "A Walk in the Clouds") but it would require retraining, etc. In regions where they plan on some winter kill, they actually train the vine trunks low and then bury them with dirt, then pull the dirt away when it warms up. Life on the fringe. (fridge? sorry)
Posted by: Tom | January 23, 2007 at 09:23 PM
Interesting...do you think the vine dies because the water in the xylem freezes and fails to make it to the needed tissue for photosynthesis/glycolysis/other plant metabolic pathways. If that is the case, warming the area surrounding the rootstock would theoretically combat "winter kill." I dont know though, i studied human physiology, not plant biology (even though it is incredibly interesting) ; )
Thank god this is the coldest time of the year. I have a feeling Spring is right around the corner.
Posted by: Ryan F | January 24, 2007 at 12:31 PM
Just submitted this post to wine life today. Everyone should vote it up to the homepage...
http://www.winelifetoday.com/shakeit.php
Posted by: Ryan F | January 24, 2007 at 12:35 PM
On "winter kill," ya got me on that one. My UCDavis days are way back there but I don't think anyone actually explained the reasons the tissue dies. With your human physiology background may have a clue, actually, because I get the sense that it's much like frostbite. I think the cells die, possibly trouble with the mitochondria or osmotic pressure in the cell walls? Hope I never have to know first-hand.
Reminds me that I should blog about the UC Davis vine and wine program sometime. Look for a post "so ya wanna be a winemaker?"
Posted by: tom | January 24, 2007 at 02:27 PM
That sounds great Tom, do you have an RSS feed for your blog. I would definitely sign up...
Posted by: Ryan F | January 24, 2007 at 09:22 PM