Viticulture

wine grapes

Viticulture (from the Latin word for vine) is the science, production and study of grapes which deals with the series of events that occur in the vineyard. When the grapes are used for winemaking, it is also known as viniculture. It is one branch of the science of horticulture.

While the native territory of Vitis vinifera, the common grape vine, is a band of area from Western Europe to the Persian shores of the Caspian Sea, the vine has demonstrated high levels of adaptability and will sometimes mutate to accommodate a new environment after its introduction. Because of this Viticulture can be found on every continent except Antarctica.^[1]

Duties of the viticulturist include: monitoring and controlling pests and diseases, fertilizing, irrigation, canopy management, monitoring fruit development and characteristics, deciding when to harvest and vine pruning during the winter months. Viticulturists are often intimately involved with winemakers, because vineyard management and the resulting grape characteristics provide the basis from which winemaking can begin.

History

The history of viticulture is closely related to the history of wine with evidence of man cultivating wild grapes to make wine dating as far back as the Neolithic period. There is evidence that some of the earliest domestication of Vitis vinifera occurred in the area of the modern day country Georgia.^[2] There is also evidence of grape domestication occurring Near East in the Early Bronze Age around 3200 BC.

The earliest act of cultivation appears to have been the favoring of Hermaphroditic members of the Vitis vinifera species over the barren male vines and the female vines which were dependent on having a nearby male to pollinate. With the ability to pollinate itself, over time the hermaphroditic vines were able to sire offspring that was consistently hermaphroditic itself.^[3]

At the end of the 5th century BC, the Greek historian Thucydides wrote:

The time period that Thucydides was most likely referencing was the time between 3000 BC and 2000 BC when viticulture emerged in force in the areas of Asia Minor, Crete, Greece and the Cyclades of the Aegean Sea. It was during this period that grape cultivation moved from being just an aspect of local consumption to an important component of local economies and trade.^[5]

Roman viticulture

Between 1200 BC to 900 BC the Phoenician developed viticulture practices that were later utilized in Carthage. Around 500 BC, the Carthaginian writer Mago recorded these practices in 28 volume work that was one of the few artifacts to survive the Roman destruction of Carthage during the Third Punic War. The Roman statesman Cato the Elder was influenced by these text and around 160 BC wrote De Agri Cultura which expounded on Roman viticulture and agriculture.^[6] The Roman writer Columella produced the most detailed work on Roman viticulture with his twelve volume AD 65 text De Re Rustica. Columella work is one of the earliest to detail trellis systems for getting vines off the ground. Columella advocated the use of stakes versus the previously accepted practice of training the vines to grow up along tree trunks. The benefits of using stakes over trees was largely to minimize the dangers associated with climbing trees to prune the dense foliage to give the vines sunlight and later to harvest.^[7]

Roman expansion across Western Europe also brought Roman viticulture to the areas that would be home to some of the world most well known wine-growing regions-the Spanish Rioja, the German Mosel, and the French Bordeaux, Burgundy and Rhône. Romans viticulturists were among the first to identify steep hillsides as one of the more ideal locations to plant vines because cool air runs downhill and gathers at the bottom of valleys. While some cool air is beneficial, too much can rob the vine of the heat it needs for photosynthesis and in the wintertime increase the hazard for frost.^[8]

Medieval viticulture

In the Middle Ages, Catholic monks (particularly the Cistercians) were the most prominent viticulturists of the time period. Around this time, an early system of Metayage emerged in France with laborers (Prendeur) working the vineyards under contractual agreements with the landowners (Bailleur). In most cases, the prendeurs were giving flexibility in selecting their crop and developing their own vineyard practice.^[9]

Many of the viticultural practices developed in this time period would become staples of European viticulture till the 18th century. Varietals were studied more intently to see which vines were the most suitable for a particular area. Around this time an early concept of terroir emerged as wines from particular places began to develop a reputation for uniqueness. The concept of pruning for quality over quantity emerged though it would create conflict between the rich landowners who wanted higher quality wines and the peasant laborers who livelihood dependent on the quantity of wine they could sell.^[10] The Riesling is the famous example for higher quality of wine. In 1435 Count John IV. of Katzenelnbogen started this successful tradition^[11].

In Burgundy, the Cistercian monks developed the concept of cru vineyards as homogeneous pieces of land that consistently produce wines each vintage that are similar. In areas like the Côte-d'Or the monks divided the land into separate vineyards, many of which are still around today-like Montrachet and La Romanée.^[12]

Growing vines

The vast majority of the world's wine producing regions are found between the temperate latitudes of 30° and 50° in both hemispheres. In these bands the annual mean temperatures are between 10 and 20 °C (50 and 68 °F). The presence of large bodies of water and mountain ranges can have positive effects on the climate and vines. Nearby lakes and rivers can serve as protection for drastic temperature drops at night by releasing the heat it has stored during the day to warm the vines. The vine needs approximately 1300-1500 hours of sunshine during the growing season and around 690 millimetres (27 in) of rainfall throughout the year in order to produce grapes suitable for winemaking. In ideal circumstances the vine will receive most of the rainfall during the winter and spring months. Rain during the harvest time can create many hazards such as fungal diseases and berries splitting. The optimum weather during the growing season is a long, warm summer that allows the grapes the opportunity to fully ripen and develop a balance between the acid and sugar levels in the grape.^[13]

Other factors that viticulturists consider is the topography of the area with hillsides and slopes being preferred over flatter terrain. A main reason for this is that vines on an angle can receive a greater strength of the sun rays with the sunshine falling on a perpendicular angle to the slope. With flatter terrain, the strength of the sunlight is diluted as it is spread out across a wider surface area. An additional benefit is the natural drainage that a slope offers so that the vine doesn't sit with too much moisture in the soil. In cooler climate regions of the northern hemisphere, South facing slopes receive more hours of sunlight and are preferred. In warmer climates, north facing slopes are preferred. (In the southern hemisphere these orientations are reversed).^[14]

Hazards

Examples of downy and powdery mildew on a grape leaf.

There are many hazards that a viticulturist needs to be aware of when growing vines. These hazards can have an adverse effect on the wine produced from the grape or kill the vine itself. When the vine is flowering it is very susceptible to weather hazards such as strong winds and hail. Cold temperatures during this period can also bring the onset of millerandage which produces clusters with no seeds and varying sizes. Too much heat can have the opposite reaction and produce Coulure that causes grape clusters to either drop to the ground or not fully develop.^[13]

Viticultural hazards include:

manual grape gathering

• Oidium
• Frost
• Powdery mildew
• Downy mildew
• Phylloxera
• Plant virus

Green harvest

A green harvest is the removal of immature grape bunches, typically for the purpose of decreasing yield. In French it is known as a vendange verte.

Green harvesting is a relatively modern practice most often used to produce fine wine. Removing the tiny, immature grapes while they are still green induces the vine to put all its energy into developing the remaining grapes. In theory this results in better ripening and the development of more numerous and mature flavour compounds. In the absence of a green harvest, a healthy, vigorous vine can produce dilute, unripe grapes.

Many traditionally renowned regions have natural conditions that suppress excess vigor. Examples include the gravelly soil of Bordeaux, the often cool climate of Burgundy, and the meager rainfall of Rioja. In these regions, the vine is prevented from producing too many grapes without human intervention. However, in regions with fertile soil, copious sunlight, and irrigation, the vine can generate huge quantities of characterless grapes. One solution is a green harvest. After fruit set, the quantity of grapes that will result from a vineyard can be estimated. Often the grower has a target yield in mind, measured in tons per acre or hectoliters per hectare. A portion of the grape bunches are cut off, to leave approximately the correct amount.

In Europe, many appellations restrict the yield permitted from a given area, so there is even more incentive to perform green harvesting when presented with excess crop. Often the excess must be sold for a pittance and used for industrial alcohol production rather than wine.

While the concept of thinning or sacrificing part of the grape crop, i.e. green harvesting, with the aim of improving the quality of the remaining grapes, predates modern critics, the practice has increased in recent times in vineyards found in California and areas where the grapes grow easily. (McCoy)

Field blend

Mechanical harvesting of Sauvignon blanc grapes in Côtes de Duras France

A field blend is a wine that is produced from two or more different grape varieties inter planted in the same vineyard. In the days before precise varietal identification, let alone rigorous clonal selection, a vineyard might be planted by taking cuttings from another vineyard and therefore approximately copying its genetic makeup. This meant that one vine could be Zinfandel and the next Carignan. When making wine with little equipment to spare for separate vinification of different varieties, field blends allowed effortless, though inflexible, blending.

Fermentation tanks are now cheap enough that the field blend is an anachronism, and almost all wines are assembled by blending from smaller, individual lots. However, in California some of the oldest (and lowest-yielding) Zinfandel comes from vineyards that are field-blended. Ridge Vineyards owns the Lytton Springs vineyards in Sonoma County, which were planted from 1900 to 1905 in what Ridge calls "a traditional field blend of about seventy percent Zinfandel, twenty percent Petite Sirah, and ten percent Grenache and Carignan."

Gemischter Satz is a wine term in German equivalent to a field blend, which means that grapes of different varieties are planted, harvested and vinified together. In older times, this was common, but the practice has almost stopped.

See also

• Annual growth cycle of grapevines
• Ampelography
• Vine training systems
• Diurnal temperature variation
• List of vineyard soil types
• Oenology
• Precision viticulture
• Winemaking

References

Further reading

External links

• LIVE - Low Input Viticulture and Enology, Sustainable Viticulture Certification
• AJEV - American Journal of Enology and Viticulture
• Grape Pest Management Guidelines (IPM) UC IPM Online Pest
• SAFECROP - Proceedings of the 5th International Workshop on Grapevine Downy and Powdery Mildew
• Viticulture and Enology at Washington State University