February 12, 2016

Heat caused Iowa grapes to ripen faster, harvest starts soon

An expert on the state’s wine industry says the grape harvest in Iowa will start next week. 

Mike White is what’s called a “viticulture specialist” with the Midwest Grape and Wine Institute at Iowa State University. In a normal year the grape harvest in Iowa begins in mid-August, but White says due to the intensity of the heat this growing season, the grapes have matured more quickly.

“This year we had a lot of heat units develop in March and we’re way ahead on heat units and then when you also bring in drought stress, it also increases the ripening time,” White says. “This will be the earliest we’ve ever harvested grapes — that I’m aware of — in Iowa.”

The number of tons of grapes to be harvested in Iowa this season will be lower — because the size of the berry is smaller in dry weather.

“You have more skin versus berry pulp and the skin adds favor, it adds color to the juice,” White says, “so often you do probably get a little bit, maybe, quality grape under drier conditions.”

There are about 300 vineyards in Iowa today covering about 1200 acres.

“Maybe 15 percent of them have drip irrigation and in that case there is no stress whatsoever in that case there is,” four or five years, more than likely they’re doing fine.”

That’s because the root systems in well-established vines go 20 to 30 feet underground. Growers who have more recently planted vines are likely irrigating, according to White. About 40 different varieties of grapes are grown in Iowa. The harvest season for grapes in Iowa normally stretches from mid-August to early October.

“Instead of going, like, August 15, we’re looking forward to about the last week of July or somewhere around August 1st we’re going to start picking grapes,” White says.

During a typical season, an acre of vines produces between three and eight tons of grapes.

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