After three stunning vintages, back-to-back, 2015 has been challenging. Though many immediately jump to the conclusion, "it must be the draught", in west Sonoma County, nothing could be further from the truth. In fact, it's just the opposite.
Halleck Vineyard has experienced "shatter". Grape shatter (or coulure in French) occurs when grape clusters do not develop completely during infancy. Either the grapevine's flowers weren't pollinated and never developed into berries, or the tiny berries fell off soon after they formed. This is referred to as "poor fruit set."
Shatter happens during the spring, triggered by rain, wind, rough handling, or extremes in temperature during bloom. Shatter can happen to any grape, but some varieties of grapes are more at risk, such as Pinot.
Flowers can be male, female or perfect. Nearly all Vitis vinifera grape varieties have hermaphroditic (perfect) flowers, containing functional male and female parts. Each of the five stamens (male pollen-bearing organs of the flower), consists of a pollen-producing anther and a filament or stalk. The female pistil consists of a stigma, a style, and an ovary. The stigma serves as the receiver of pollen.
Cool, wet or even overcast weather can reduce fruit set. At each stage (floral initiation, development, bloom and fruit set) the weather can cause damage. Cold and overcast weather prior to bloom leads to problems with floral development. Cold weather during bloom can cause a delay in the blooms development and lead to reduced set.
Rain during bloom is the ultimate fear of any grape grower and occurred in early March of this year, 2015. Rain physically inhibits pollination and fertilization. Hence, we have a spotty crop of less than 30% of the previous three vintages of 2012, 2013, and 2014. So here we are, suffering from a draught with a fraction of the annual expected rainfall; then we get two days of rain in June, during the 36 hour window of pollination.
Shatter is the perfect term for this condition; the hopes and dreams of a bountiful harvest are shattered!. In truth, there's always some amount of shatter. It's not feasible that every flower forms into a berry. The vine wouldn't be able to provide nutrition to all of the fruit and ultimately die. As with everything in life, there are varying degrees of shatter. Some are expected and acceptable. While others are devastating.
With our harvest days away and our Harvest Party just a couple of weeks, this is an anxious time.
2015 is one of those difficult years.