In the December 22, 2022 Vineyard Update newsletter, I wrote about the new website for the Grapevine Cold Hardiness project, which is now being led by Jason Londo. In it, I tried to describe how the new site was essentially presenting the same data as the previous website had done, but with a lot more as well. I won’t bother to reproduce that article here, but you can click on the link above to read it again if you want.
I’ve received a few questions lately about bud and vine hardiness given the winter that we’ve had so far. There has especially been some concern about any damage that might have resulted from the rapid temperature drop that happened on December 23 (about 35-40°F colder in 10 hours). Fortunately, none of the weather stations in the Finger Lakes that we monitor on the NEWA network dropped below 0°F, and at that point, bud hardiness was good enough that they should not have been overly threatened by the cold temperatures. We have been on the lookout for cracked trunks as a result of the temperature change as well, but to this point, we haven’t seen much that we could likely attribute to that event. If any growers are finding a lot of cracking lately, please let me know.
The following is the current status of bud hardiness (LT50 readings) for some of the cultivars included on the project website. The ‘Measured’ results are from freezer tests similar to those we have used for many years to determine LT50 values. These results are based on vineyard samples collected last week near Geneva. The ‘Modeled’ results are updated as of yesterday, January 16, and based on the winter hardiness model that Jason and his lab has been developing for several years. And just for kicks, I’ve added the LT50 values for each cultivar on January 10, just before the first of the two cold weather events last year that ended up causing vine injury and death in many vineyards.
| Cultivar | Measured LT50 (°F) | Modeled LT50 (°F) | 1/10/22 LT50 (°F) |
| Cabernet Franc | -9.0 | -11.6 | -2.8 |
| Cayuga White | -10.9 | -11.4 | 1.0 |
| Concord | -15.5 | -16.1 | -4.5 |
| Chardonnay | -11.0 | -11.9 | 0.2 |
| Gewürztraminer | -8.7 | -9.2 | 6.9 |
| Marquette | -9.2 | -16.2 | -11.0 |
| Riesling | -9.0 | -12.5 | -3.0 |
As you can see, the buds for all cultivars except Marquette are much hardier this year than they were at this time in 2022. In Marquette, it seems there was some more significant deacclimation of the buds during the warm spell that followed that rapid cooling event, with temperatures reaching 60°F in Geneva on December 31. We’ll see how Marquette reacts over the next week or two to the more seasonal cold that we have been having lately.
Just as a final note, we have also started to dissect some buds from the Teaching Vineyard to “ground truth” the lab data. We will have more results in the next several days, but so far we have seen almost no injury in Grüner Veltliner (2.3% damage), Riesling (1.1% damage), and Cab Franc (0%).
