Nov 6, 2012
Michigan grape season varies across state

Northwest Michigan wine grape growers are expecting a pretty good season, said Duke Elsner, a small fruit educator with Michigan State University (MSU) Extension.

Wine grape buds naturally break dormancy quite a bit later than typical juice grape cultivars, Elsner said. The extremely warm weather in March did not last long enough to awaken the dormant grape buds. Growers may have lost a little bit of dormancy and cold-hardiness, but for the most part this was insignificant and the new grape shoots that came out later in the spring looked great, he said.

“We came into early September still a good two weeks ahead of the normal fruit developmental pace, and early varieties were harvested about two weeks earlier than usual,” Elsner said. “Then the weather changed significantly and the pace of ripening slowed to a crawl for the rest of the fall. We saw later varieties being harvested at normal or even later than typical dates.”

2012 was a tough year for Southwest Michigan grape growers, said Mark Longstroth, a small fruit educator with MSU Extension. The season began very early with the warm weather in March. Juice grapes had reached bud burst to second leaf by March 26, while most wine grape varieties were still at late swell, he said.

“Grapes were down because of the freezes, so yields were light,” Longstroth said.

Temperatures dipped into the mid-20s on April 7, causing significant damage to many vineyards. Another severe freeze on April 12 caused additional widespread damage. As a result, many vineyards lost most primary buds. Yet another freeze on April 28 took out the majority of grapes that had missed being damaged by the earlier freezes, Longstroth said.

Growth from secondary buds took several weeks to get large enough to be susceptible to freeze injury, so many of the shoots from secondary buds escaped the freezes in late April, he said.

Wine grapes fared better and fewer were damaged. Still, losses were estimated at 10 percent to 50 percent, depending on location in the state. The grapes that were harvested were very sweet.

“The grapes made lots of sugar, so the sugar levels at harvest were high,” Longstroth said.

Incidence and severity of most diseases was also lighter than usual this season. A dry summer reduced disease pressure for most foliar diseases. Favorable conditions for downy mildew and powdery mildew didn’t occur until late in the season, past the time when they would do much damage to fruit, Longstroth said.

According to reports from growers, harvest of Niagara juice grapes began Sept. 4, at least 10 days earlier than last year, and harvest of Concords began Sept. 14, more than two weeks earlier than last year. With all that occurred this season, yield was down also, Longstroth said.

“Yields were probably about a third of normal and most growers did not make a profit,” he said.

Despite the cool and rainy conditions, Northwest Michigan fruit quality has remained very good, Elsner said. Color and flavor development has been outstanding for many varieties.

“We are still expecting this to be a very good vintage year for northwestern Michigan wines,” he said.

By Derrek Sigler, Assistant Editor

75 Applewood Drive, Suite A
P.O. Box 128
Sparta, MI 49345
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