Grape growers are struggling to recover from a rare run of cold nights that have destroyed as much as half of some farmers' crops, agriculture officials in New York, Ohio and Michigan say.

A drop in temperatures to the low 20s on April 26 likely caused more than $1 million in damage to juice and wine grapes in Ashtabula County, said David Marrison, a county agricultural official in northeast Ohio.

“There are some people in their 70s here who have been farming all their lives and have never seen this bad of a frost or a flash freeze,” he said.

Temperatures also dropped below freezing April 28, May 7 and May 23.

The frosty nights also affected grape crops in Michigan and New York.

The National Grape Cooperative Inc., which owns Welch's and contracts with 1,400 farmers nationwide, estimated that its New York farmers lost 30 percent of their crop.

The cooperative's growers in Michigan may have lost as much as 90 percent, according to Jay Hardenburg, the cooperative's Eastern Region manager of member relations.

Farmers who grow Concord and Niagara grapes, used in making juice and jam, suffered more than those who grow wine grapes, said Michelle Widner of the Ohio Grape Industries Committee.

That's partly because wine grapes tend to show their buds later in the year than juice grapes.

Most of Ohio's damage took place in Lake and Ashtabula counties, but some vineyards in central and northwest Ohio had losses of 30 percent to 50 percent, said Donniella Winchell, executive director of the Ohio Wine Producers Association.

Wine and juice grapes are vulnerable to damage when temperatures drop below 32 degrees for more than several hours. This year was unusual because there were four nights within a period of a month, making it difficult for vines to grow new buds to replace the young ones that ruptured after the first freeze.

“It was like a triple whammy. The plants began to recover from April 26 and then a few days later it happens again,” said Imed Dami, a wine grape expert at the Ohio Agricultural Research & Development Center in Wooster. “Every time they begin to grow they have a setback.”

Because it is so rare to have such low temperatures so close together, most farmers do not carry catastrophic insurance, Marrison said.

Growing conditions have been usually good for the last several years, but farmers will take a loss on this year's crop. Most will be able to pull through on earnings from last year - one of the best in recent memory, Marrison said.

Agriculture officials will assess damage once grapes begin to fully form on the vine in the next month or two, Dami said.

Reports have been sent to the U.S. Department of Agriculture, but it is too early to tell if federal disaster aid will be needed, he said.

The state government has been trying to persuade growers to switch to wine grapes because of their resilience and their higher financial return, Widner said. More grape growers are making the change despite its expense, she said.

“Grape growing is a growth industry in the state of Ohio,” Widner said. “This year, we'll be set back a bit.”