#83 One-Year Anniversary: 27 Degrees
Was this a "once-in-a blue-moon" event, or will it be the norm?
One year ago, in 2023, temperatures hit 27 degrees on May 18 and stayed there for five hours. This freeze damaged young grapevine shoots throughout New York State. It also became a benchmark date. Now we know we can get frost as late as May 18.
This year, the forecast for May 18 is a high of 67 degrees and a low of 54 degrees. We are not worried. Not for this year.
Our colleagues at Cornell are taking note of all this (see Substack #78). Every year, they track when “bud break” occurs for different varieties of grapes. “Bud break” is when it is possible to see fragile leaves emerging from the bud along the grapevine cane.
For Riesling, the average date of bud break between 2018 and 2022 was May 11. In 2023, bud break was April 26, fifteen days earlier. A very warm April in 2023 caused the vines to accelerate their growth. That early, accelerated growth led to six-eight-inch shoots on the vine when the late frost hit on May 18.
Including the much earlier bud break of 2023, the six-year average, 2018-2023 is now May 8. That makes this year’s bud break of May 1, seven days earlier than the average. This is something to watch. We may be seeing warming trends AND more erratic weather events (like late frosts.)
So, what to do about this?
One option for late season frost involves wind machines to circulate stagnant air on particularly cold nights. These are expensive machines, which may only be used infrequently. (They would also interrupt our very nice view of Seneca Lake.)
Another option is distributing “smudge pots” which burn petroleum products, throughout the vineyard. In recent years, we have seen these used more and more frequently in vineyards in Europe.
Experiments are underway to see if it is possible to delay bud break in the spring by applying a chemical (gibberellic acid) to the buds at just the right time during dormancy. Studies like these are likely to take years to yield conclusive results.
So, we have options should the current climate trends continue. But, unfortunately, none of them are desirable.
I suspect you will conclude that there is nothing you can do to effectively impact bud break. It has to be one of the biggest risks of farming in somewhat marginal areas.
My first year growing corn we had a Memorial Day (May 25th that year) hard freeze after a warmer than normal April and May; the corn was close to knee high at the time. We made a serious error in choosing to replant; the corn that we left yielded near normal and the replant (which cost an extra $100 an acre) was 30% less. It nearly bankrupted me.
The next year, after a cooler than normal summer blamed on volcanic activity the previous year, we had a hard freeze and snow on September 13th taking about 1/3 of the yield off, again almost bankrupting me. Back to back years, 1992 and 1993. Normal frost dates are May 15 and Oct 1st in my area, NE Colorado.