The winter of 2021 – 2022 came in easy as was the last few years. Warmer than normal temperatures dominated in December into early January. I was both thinking and hoping that the pattern would hold as long as it could. Then the wind changed. Yes, I felt it, and it was true. Suddenly we started to see the single digits for the low of the day. That made me nervous. When it plunged into the negative territory, a red flag popped up. “It’s not good.” I couldn’t even remember immediately when we saw a negative number last time.
Grapes are generally a plant in a temperate region of our Planet. So when it gets colder than certain point, they simply don’t survive. They start to lose their live buds on the canes when temperatures dip below their limit. Sometimes their trunks split. Eventually the whole grapevines can die from extreme cold.
I saw the negative numbers in my vineyards twice in January: -4.5 and -1.7 degrees. And about a dozen of single digits in January and February. I was getting ready to go out to obtain some sample canes of each variety we grow in the vineyards to test so-called bud mortality rate before pruning the vines. We have to make an adjustment of how many canes to leave on the vines depending on this rate to maintain the crop level at harvest. More dead buds, more canes to stay on the trellis.
So I went out and brought back an armful of grape canes. They were placed in the water in a bucket and stayed in a comfortable temperature to “wake up” for a few days. Honestly, I don’t remember when I did this last time – we were so used to having a mild winter that did not give me any alert to cut the buds. But, well, here I’m going.
This is a cane of Cayuga White. What I do is to slice the buds on the cane in half and look inside. Is the bud green or brown? If it’s green, that’s the sign the bud is alive and likely would grow into a shoot to bear grapes in fall. The arrow is pointing at the bud sliced off from the cane. Can you see the center of it is bright green?
On the contrary, this is a Riesling bud. It looks brown meaning it’s dead. I keep cutting each bud on the canes and come up with a tally in the end. That will give us an idea how to prune the vines this spring.
While cutting the buds of Riesling, I noticed that most of the dead buds are toward the end of the canes. Hmm… I tried to recall what might have been going on to cause it. Eventually I came to suspect that many of the vines got downy mildew on the tip of their growth last summer. Perhaps the disease hindered the buds from attaining enough cold hardiness to get through the extreme temperatures. — I have to come up with a better spray program for this season. I sit and cut the buds and listen to the vines’ stories. (By the way, the bud mortality rate was not so high that made me feel relieved…)