Why Grape Shatter Happens
April 10, 2008
Recently, we had a question from one of our readers - Ferhat, hailing from Istanbul, Turkey asked: Could you tell me why grape shatter happens please?
Ferhat, absolutely…
You see, small grapes have a tiny end on them which functions basically like a cap. As the grapes grow larger these caps fall off. But sometimes during a cool, wet spring… like how we are having right now in the southern U.S., a crop of grapes can fail to develop properly and this will lead to the cap at the end becoming very tough.
Now, when the warm weather of summer finally arrives and as the grape matures on the vine, it will begin to push up against this cap that is now very tough. The end result being is that instead of the cap falling off as it normally would, the grape actually shatters against the cap due to the pressure of being pressed up against it. When this occurs it can destroy whole yields and leads to what is known as a poor fruit set with bunches that only have a few grapes.
Grape shatter is a major concern that puts many vineyards at the mercy of the weather each and every year. Also, as a tid bit of wine trivia for you, grape shatter is known in French as Coulure. Click on that term and you will find some more info on the different ways that grape shatter can happen and the other problems that stem from it.
Ferhat, great question and I look forward to hearing more from you again along with our many readers out there that are curious about this beautiful and wonderful drink. Cheers!!
Coulure
March 24, 2008
Hey could you tell me what grape shatter is please? - Jeanie in Beaumont, TX
Grape shatter which is known as Coulure in French happens when a grape cluster does not fully mature. This is due from either the grapevine’s flowers not getting pollinated or that the berries fell off soon after they formed.
Coulure is triggered by periods of cold, cloudy, rainy weather or very high out-of-season temperatures and the condition is manifested in Spring. Varietals with high proclivity to couloure are Grenache, Malbec, Merlot, and Muscat Ottonel. Other causes of coulure may be vineyard conditions and practices, pruning too early or too severely, excessively fertile soils or overuse of fertilizers, and improper selection of root stocks or clones.
Coulure can also cause irregular bunches of grapes which are less compact than normal. These bunches are more sensitive for diseases. The yield of a vine with coulure will decrease substantially and is what is meant by the term “poor fruit set.”
See, this is why you should always be grateful for that perfect bottle of wine. Think of all the poor, poor souls in the past who literally had their hopes and dreams for lush moments shattered. Drink solemnly in remembrance of their loss. Amen.