What a late spring freeze means for fall apple crops, expert explains
Spring freezes can have a devastating effect on fruit crops when they occur during bloom. This year's freeze events were especially severe in the Winchester and Frederick County area of Virginia, where apple and peach crops were essentially wiped out.
Virginia Tech fruit crop expert Sherif Sherif explains why the conditions of this year's freeze made such a difference. “I believe the reason was not only the low temperatures we experienced, but also the duration of the freeze events and the very dry air, reflected in the unusually low dewpoints,” said Sherif. “I believe the combination of these conditions contributed to the severe damage we observed this year.”
Why is this year's freeze different?
Freeze damage has occurred every year since Sherif began at Virginia Tech in 2017, but this year marked the first time he observed an essentially 100% crop loss in the area.
“You can have temperatures around 19 degrees Fahrenheit for 1–2 hours, and the buds may survive, mainly because they are not as developed yet. In other cases, you can have 23 degrees Fahrenheit for just one hour, and that may be enough to kill 90 percent of the buds at the full-bloom stage. With no flowers alive, you simply don’t have fruit.”
What is the impact on consumers?
“Most of the pick-your-own operations in the area did not have fruit to sell this year, and the same was true for wholesale markets and many farm markets,” said Sherif, regarding commercial impact of this year's freeze. “Having said that, there are parts of the state, such as Nelson County and areas of central Virginia, that were not exposed to the same severe freeze events. To a greater extent, those areas escaped the destructive freeze damage we experienced here and were still able to set a commercial crop.”
Is there a way to prevent this?
Virginia Tech researchers are studying several approaches to help growers reduce the effects of spring freezes, Sherif said.
“In my lab, we have developed and evaluated several frost avoidance and mitigation methods over the past few years, including bloom-delay reagents to help avoid spring freezes and coating materials that can insulate flowers during a freeze event. We have also been evaluating cryoprotectants designed to lower the freezing point of flower buds and help them survive subfreezing temperatures.”
While none of these approaches were sufficient in the context of this year’s freeze events, Sherif says he and his team are not giving up.
“We are also working on developing new varieties through gene editing that are more freeze-tolerant, while continuing to optimize some of our current methods to better help growers survive devastating events like the ones we experienced this April.”
About Sherif
Sherif Sherif is an associate professor within the School of Plant and Environmental Sciences at Virginia Tech. His research focuses on environmental, biological, and genetic barriers that limit the production and/or profitability of pome and stone fruits in Virginia.
Interview
To schedule an interview with Sherif about spring freezes, fruit crop damage, and frost mitigation, contact mediarelations@vt.edu.
