A milder winter has raised some concerns among experts when it comes to the upcoming fruit crop season.

Following the more mild winter, freeze resistance in fruit crops is lower than what it would be with lower temperatures, causing specific concerns about any potential major cold events later in March, early budbreak and potential frost risk.

Jennifer Phillips Russo, Lake Erie Regional Grape Program team leader and viticulture extension specialist, said while she has not heard or seen any damage to grapes yet this season, the warm weather is still a slight concern.

“Grapevine phenology and fruit ripening are greatly affected by temperature conditions,” Russo said. “A grapevine goes into dormancy in the fall to become acclimated to the cold weather to survive the cold temperatures. This acclimation process is influenced by temperature. Grapevine buds gain cold hardiness as temperature decreases. As the late winter months begin to warm up, then the grapevine buds begin to de-acclimate with the warming weather. We have experienced a mild winter thus far with punctuated acute cold weather.”

At the Cornell Lake Erie Research and Extension Laboratory in Portland, 15 different cultivars are monitored weekly for cold hardiness. Lake Erie, which buffers the climate in the local area and provides great potential for grape production, has been warmer this year, never icing over. Russo said this may affect grape production.

“The ice boom was removed, and it was noted that the last time it was removed this early was in 2012,” Russo said. “2012 was a hard year on grapevines with an early budbreak due to unseasonably warm early spring weather with the official budbreak date of April 25, 2012, which was 11 days earlier than the historical average and then experienced many freeze events after the green tissue was exposed. Naturally, there is some trepidation and concern with similar conditions this year and if unseasonably warm weather persists.”

For a few different types of grapes, buds should be safe until temperatures reach about negative three degrees Farenheit or lower. Russo said the good news for the buds is that sap flow does not necessarily impact hardiness itself but this might not be great news from a trunk freezing point of view.

“As the soils warm up from the higher temperatures, it triggers sap flow in the woody portions of the vine,” Russo said. “That sap moves and clears out a lot of the sugars needed to reduce freezing tolerance. There isn’t really anything we can do about it though, apart from watch with held breath. There is a risk of trunk splitting with the extreme shifts in temperature as that sap fills the woody portions of the vines and then quickly freezes and expands.”

Russo encouraged growers to take a lot of pictures and send them to the Lake Erie Regional Grape Program if they experience any trunk damage due to swelling of the vines and then experience the quick drop of temperatures to freezing. She added that there are some things that growers can do if frost events come up.

“There are risk management strategies that growers can employ when making their pruning decisions regarding their bud number that include leaving up more buds on the vine as insurance should frost or freeze events threaten,” Russo said. “However, the growers must then make thinning adjustments after budbreak to balance their vine for a healthy and productive season.”