A disease affecting grapes, esp. in California, manifested by the premature dropping of the fruit.

A vine condition that adversely effects yield. Soon after flowering, immature, under-nourished grapes dry up and fall from the vines. It is impossible to prevent coulure altogether, but good weather conditions and careful growing practices can minimize its effects.

(France) Once the vine has flowered, there should develop a small fruit (the grape) in place of each flower. Failure of the fruit to set in this way is coulure. It is often worst when the weather is particularly cold or wet. Some coulure is beneficial as a vine would have difficulty in ripening a full crop, resulting in a reduction in quality - although this can be adjusted for with a green harvest. Heavy coulure will result in a very small crop.