Jason Londo

Cold hardiness refers to the tissue’s ability to survive freezing as cells control their hydration levels, making it harder to form ice crystals.

April 26, 2023

Mild Winters Can Affect NYS Grape and Apple Crop Production as Spring Weather Warms Up Region

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Mild winters weaken the cold hardiness of apples and grapes, according to researchers in the AgriTech Campus who are studying fruit crop physiology and climate adaptation, led by Prof. Jason Londo, horticulture. This can lead to early bud break and higher risk of frost damage. 

Cold hardiness refers to the tissue’s ability to survive freezing. “The cells control their hydration levels and they put the water conformations so that it’s harder to form ice crystals,” Londo said. 

The effects of cold hardiness on the dynamics of apple and grape physiology is relatively unknown, which is what Londo’s lab is further investigating. However, they know that the only similarity between apples and grapes are that they are both perennials, meaning they are adapted to annual cold periods and changes in light. 

The general pattern of cold hardiness in plants forms a U-shape curve, exhibiting weak defense mechanisms in the beginning of winter, evening out during the lower temperatures of the winter months and then losing the defense mechanism during bud break as a result of warmer spring weather. 

Londo and his team measured points on the curve throughout the months to track the progress of cold hardiness before, during and after winter for both grapes and apples. 

“The depth of that ‘U’ is shallower…we have less defenses this year and that’s because it’s not been as cold as it has been in the past,” Londo said. 

He goes on to note that it is not the mild winters itself that are weakening the crops’ winter hardiness, but rather the fluctuation in weather patterns. 

“The issue comes with the erratic nature of climate change. We’re getting more mild so our curves are shallower, but we also have punctuated cold because we’re in New York,” Londo said. 

Londo pointed out that Ithaca experiences polar cold because of its northern latitude location that causes the polar cold to hit this region more frequently.

“Those sharp cold events are what we’re worried about because if you don’t defend yourself well, you take damage,” Londo said. “If you take damage in both of these systems, in both of these buds, you have reduced yields because you kill the flowers before they have a chance to be opened and be pollinated.”

The effects of winter hardiness differ based on the variety of apples and grapes. For example, some varieties exhibit much more cold hardiness — a deeper ‘U’ — and reach bud break much faster. Londo notes that these types of cultivars are at higher risk of frost damage because they respond to warm temperatures much earlier in the season and lose the defense mechanism at bud break. 

The physiological differences among cultivars signify the importance of crop diversity because it ensures that erratic weather conditions will not eliminate all crop varieties, but rather a select few.  

Studying different crop varieties has given Londo a better understanding about plant physiology in order to prepare for future weather occurrences.  

“[Crops] are used to only responding to heat because it means spring, but when we have a really warm winter, they respond to heat thinking spring is earlier,” Londo said. “So if we understood that signaling and we could manipulate it, then we could keep them down and dormant and protected when we have years like this.”

With erratic weather patterns throughout the month of April and a relatively mild winter, Londo emphasized that building resiliency into the framework of crop production is key in fostering sustainability for both farmers and consumers.