Warm Winter, Frosty Spring Spell Trouble for NY Grapes, Fruit Trees

5/11/2012

        The combination of an unusually warm March that triggered early growth at area orchards and vineyards, with several nights of sub-freezing temperatures in late
April, has led to potentially devastating damage to apples, cherries, grapes and other of the region's vital agricultural crops. Cornell University researchers and Extension specialists have been working with area growers to assess the situation, and several comment here on what this "inverted" spring might mean for producers and consumers.



        David W. Wolfe is a professor of plant and soil ecology in the College of Agriculture and Life Sciences, and the chair of the Climate Change Focus Group in the Atkinson Center for a Sustainable Future.

        "Even in the context of a changing climate with a trend for warmer winters, this year was an extreme, and many of the region's tree fruit crops broke all records by leafing out and flowering a month or more earlier than normal. Apple, grape and other tree fruit growers have been holding their breath, knowing their crops would be highly vulnerable to frost damage.

        "Unfortunately, April has included several nights dipping well below freezing, and many parts of the region experienced a wet, heavy snow event that damaged trees. A full assessment of the effects on pollination, fruit loads and fruit quality will take some time, but early reports from the field suggest there could be a major negative effect on New York's agricultural economy."



        Hans Walter-Peterson is an Extension associate with the Finger Lakes Grape Program, who works with growers to provide research-based information to help improve profitability, product quality and business sustainability. He says:

         "It's still pretty early for us to tell the amount of damage to grape crops. We'll know more in the next few weeks as the shoots grow out more, as most of the vines are still pretty early in their development.

        "As of right now, it looks like something that growers can live with for the most part. Our initial estimate is that damage is generally in the range of 10 to 30 percent, but that is very dependent on varieties and locations. We won't know how this will impact yield for at least a month, but at this point consumers shouldn't worry about shortages of grape products."



        Alan Neil Lakso is a professor of horticulture and a fruit crop physiologist with expertise in the management of apple and grape growth, and how growers can respond to the environment. He says:

        "This year shows the complex way climate can affect perennial fruit crops that must survive all year long.

        "The warm winter did not cause damage due to extreme mid-winter low temperatures, which was good. But March was so warm it especially induced tree fruits to start to grow too soon. The freeze conditions in April have not been that extreme compared to normal weather, but the trees just became too tender due to their abnormally early development.

        "We have seen this pattern occasionally in the past, but with warming winters we expect it is likely to occur more frequently in the future."



        Jonathan Comstock is a research support specialist in Cornell's Department of Horticulture who specializes in the impacts of global climate change on New York. He says:

        "This year's weather patterns were something of a worst-case scenario for many of this year's potential fruit crops.

        "The abnormally mild winter led trees and vines to begin expanding overwintering buds.  As the new buds open, expand and develop into flowers and leaves, the tissues become more and more susceptible to frost damage. Very warm temperatures in late February and March accelerated this progression towards flowering, and then the repeated April hard freezes killed the flowers and many expanding leaves. The combination of this degree of early warming followed by a return to such cold temperatures is very unusual.

        "The trees and vines themselves will generally recover from these stresses, but this year's fruit crops may have been lost or decimated over large areas of the state this year."