According to Jerry Smith, owner of River Ridge Winery in Commerce, Mo., vintners want little to no rainfall after late June.Vintners need it to be dry when they harvest their grapes. With drier weather, the juices in the grapes will concentrate which will increase the sugar levels.Too much rainfall will be soaked up by the grapes and it can dilute the concentration and sugar levels.
“We’ve had way too much rain. We’ve got a good crop of grapes overall. We’re producing some really good quality wine but it’s taking a significant amount of money for additional fungicides and labor to see that that takes place,” Smith said.
Vintners measure the ripeness of grapes based on its sugar, acid and tannin levels. Grapes with balanced levels produce the best product. Vintners look to harvest grapes that measure between 20 and 24 percent sugar.
A heat wave can cause the maturation or ripening process to occur faster. Ideally, vintners want a cool winter with a good amount of moisture, followed by a subtle transition into spring with low moisture.
Sven Svenson, an associate professor of agriculture at Southeast Missouri State University said that last spring was cooler in the Midwest than most years and that caused grapes to become more susceptible to diseases.
“[They’re] not as delayed as last year and that’s the heat. Until recently we really haven’t had an extreme amount of heat, at least for Southeast Missouri and that means the grapes in that sense are on schedule but some of them are delayed from the earlier disease cycles in the spring,” Svenson said.
This year, some grapes that tend to ripen early, such as chardonnay and pinot noir,are now arriving earlier. In some minor cases, the grapes that tend to ripen later, like cabernet, can arrive even later into the season. Svenson said the ripening and harvesting process varies from variety to variety.
“The different varieties are going to have different harvest dates that Mother Nature dictates. It’s hard to pick a calendar date and set a crew to arrive on a particular calendar day or date,” Svenson said.
Brett Morrison, owner of Starview Vineyard in Cobden, Ill., said the weather was more mild this year which has been a positive factor for his crops in comparison to last year.
“This year is on schedule. Again, it looks pretty much so like a picture perfect year, other than this heat wave. It won’t affect the fruit, it’s just going to make it ripen that much faster than we anticipated,” Morrison said.