With the high levels of cold injury that we saw in Niagara last year, and the cold temperatures that are anticipated this evening, many grape growers are concerned about winter injury.
The good news for grape growers is that compared to 2021 crop the 2022 harvest wrapped up early and had much less rainfall. As a result we have reason to believe that the vines had ample time to harden off in preparation for this winter.
CCOVI did not collect any cold hardiness data last year, however, the preliminary data from this year suggests that despite the mild temperatures in the fall, grape vine hardiness is on par with 2020/2021 season, so hopefully vines are more tolerant of cold temperatures this year.
With a cold temperatures (-19 C) settling over the area tonight and tomorrow morning, it is important that growers are aware of current cold hardiness susceptibility for their grape cultivars, and temperatures in their vineyards so they can use tools ( wind machines) to mitigate winter injury.
Growers that have wind machines, should consider referring to best management practices for using wind machines and CCOVI wind machine research for information on the use of wind machines in vineyards. For optimal use of wind machines, CCOVI recommends that the start-up temperatures be set at 2 to 3 degrees warmer than temperatures at which injury might occur. Be sure to monitor wind speeds, inversion strength, and temperatures when using wind machines.
It is important to keep in mind that some of the vines that were damaged last year, may be more vulnerable to cold injury this year, and may be more susceptible to cold injury at warmer temperatures.
After the cold event, be sure to check out your vineyards to assess cold injury. Information on pruning vines after a cold event can be found at https://brocku.ca/webfm/Cold_Injury_2014._OFVC.pdf. CCOVI will be conducting bud survival assessments in the upcoming weeks to determine the impact of cold weather on primary bud survival.
For more information on winter injury in grapes, be sure to attend the grape session at the Ontario Fruit and Vegetable Convention (OFVC) where Dr. Jason Londo, Cornell will be presenting on his research with grape vine winter injury models, and Dr. Jim Willwerth, CCOVI will talk about the cold injury damage that occurred last year.