COULURE (French) or
SHATTER (English) is the consequence
of metabolic and weather conditions that cause either the grapevine flowers
to not pollinate, so they do not becomes berries, or the tiny berries
to fall off soon after they form. This means a poor fruit set. Depending
upon the severity, the net result is low or poor quantity, or even no
crop at all. This condition occurs in vines that have
too little sugar content in their tissue. It manifests in the Spring blooming
period of the vintage year and is triggered by periods of cold, cloudy,
rainy weather, or unseasonably high temperatures, both of which may interrupt
or retard photosynthesis. Shatter may occur in any varietal. Certain
varietals, however, have a high proclivity, including grenache, malbec,
merlot, and muscat Ottonel. Vineyard conditions and practices can also
cause the condition; pruning that is too early or too severe, excessively
fertile soils or overuse of fertilizers, and improper selection of rootstocks
or clones may bring aboout shatter.