January 31, 2015
4:03 pm

Winter Was Rough on Wine Grapes

Some of the bloom is off the rose when it comes to early reports of Michigan fruit crops avoiding damage due to the brutally cold winter we've come through. As crop development advances, damage to wine grapes is becoming more evident. That's the assessment of Michigan State University Extension experts Mark Longstroth and Bill Shane.

Longstroth's "Southwest Michigan Fruit Regional Report for April 29, 2014" says, "We are seeing the impact of winter cold more and more as the season starts and bud growth is slow to start." He adds, "Grapes are proceeding slowly. Early bud swell is underway and some vines are still "bleeding" from pruning cuts. In general, 'Concord' shows little damage from the winter cold. 'Niagara is much more affected with more damage, especially in poorer sites. Vinifera wine grapes are showing a lot of damage from the winter with the more winter-tender reds showing more damage than white fruited varieties that are generally more winter-hardy."

The report goes on to say that "Damage will become more apparent as buds break and green shoot growth begins. At the time flower clusters are exposed, it will be easier to estimate crop and loss. Grapes require warmer temperatures than other Michigan fruits. Grapes use a higher base temperature (50 F) than other fruits whcih us 45 F."

Longstroth and Shane say that as buds develop and blossoms appear it is easier to assess damages.

Some of the berry crops have sustained damage as well. The fruit report notes, "Brambles are showing more winter injury as growth begins. Early varieties have leaves unfolding while most varieties have about 0.25 inch of the leaves out of the bud. Winter damage to overwintering canes is severe in many plantings. Damage is most severe in thornless blackberries, then red raspberries, with black raspberries least affected."

On the upside, the MSU report indicates the apple crop has fared well. "Apples," it says, "do not show any sign of having suffered from the winter." Additional reports show:
  • Apricots are in bloom...
  • Peach fruit buds are at red calyx for the non-showy tyhpes and first pink for peaches with showy blooms.
  • Sweet Cherry buds are at tight cluster to first white. We will probably see the first blooms by the weekend or early next week. Many buds have swollen but do not appear to be opening; these buds do not have viable flowers in them.
  • Japanese Plums are at white bud and will open soon. European Plum buds are at tight cluster.
  • Blueberry flower buds are bursting in early varieties. Southern areas in Berrien County are generally more advanced. Many fields show poor growth and a light fruit bud set as a result of last year's heavy crop. Winter injury to blueberries is becoming easier to see. In some cases, last year's vegetative shoot tips are withered and terminal fruit buds are dead and shriveled.
  • Straweberries generally show very little winter injury. New leaves are emerging from the crown.

The detailed report says that much of Southwest Michigan suffered its coldest temperatures in early January with temperatures below -10 F across the region and many lows near -20 F. That is well into the range where one would expect to see damage in small fruits. Differences in growth between varieties that were able to withstand the cold and those that suffered damage are becoming apparent and will become much more noticeable as growth continues.
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Topics : Environment