Coulure

Source: Wikipedia, the free encyclopedia.
Not to be confused with Collioure AOC.
Young grapes are most susceptible to coulure right after flowering when they need vital carbohydrate resources in order to develop fully.

Coulure (pronounced coo-LYUR) is a

clones.[1]

During the flowering part of the

growing season (May–June in the Northern Hemisphere, November–December in the Southern Hemisphere), grapevines often need dry conditions with sufficient sunlight and ambient air temperature around 15 °C (59 °F) for pollination to go smoothly. Less ideal conditions, particularly wet, rainy weather, increases the odds that a higher than normal numbers of flowers go unpollinated and coulure to occur.[2]

Coulure is a distinct phenomena unrelated to another viticultural hazard, millerandage, where the flowers are pollinated but the resulting berries develop without seeds and remain small. Like coulure, millerandage is often caused by inclement weather during the flowering and fruit set period and cause reduced yields.[2]

Cause and effect

Grapevines need a balance of sufficient leaf cover in order to produce photosynthesis but not shade the grapes too much from sunlight.

Coulure is caused by a

stems
connected to the berries shrivel as the small grapes (0.2 inches/5 millimeters in diameter) eventually fall off.

Most likely a clear example of coulure.

To some extent coulure and the dropping of fruit is a natural and healthy reaction of a vine that is self-regulating its resource and the amount of fruit that it produces. But when the situation is exacerbated by certain weather conditions and disruption to photosynthesis, coulure can have a more severe impact on yields that may negatively affect a region's grape supply and thus influence pricing.[1]

When the weather is the primary instigator of coulure, the French term this phenomenon coulure climatique. This describes the cloudy and wet conditions that limit the amount of photosynthetic activity that takes place during the flowering cycle of a grapevine. Limited sunshine means lower sugar levels that can be converted into resources to develop grape berries. Warm temperatures can also exacerbate coulure in some grape varieties by promoting

vineyard soils, either naturally or enhanced by the use of nitrogen-rich fertilizers, overly vigorous rootstock and severe pruning that too drastically limits the amount of leaf surface needed to sustain photosynthesis.[1]

Prevention

Malbec can be highly susceptible to coulure but newer clones are being produced with less sensitivity.

Coulure is not 100% preventable but a vineyard manager can take several precautions to lessen the severity and impact of coulure. Some grape varieties are more prone to develop coulure than others, such as

organic viticulture, chemical growth inhibitors can be applied to the vine to limit shoot growth as well.[1]

References

  1. ^
    ISBN 0-19-860990-6
  2. ^
    ISBN 9781905819157

External links
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