wine course 2

Wine Course 2


The Vineyard
 
Wine Course 2 – The Vineyard
Like all form s of agriculture, the growing of vines is influenced by the climate, the weather, the soil and the type of grape grown. It is also influenced by the method of growing the vines and the control of pests and vine diseases. The object of viticulture is to produce the best quality grapes from the available soil. These grapes should be well balanced between the sugars, acids and tannins to produce the style of wine desired. In modern times, grape production has been increasingly subjected to science based technology and some producers are now growing grapes on an industrial scale.
1) The Type of Grapes
Most quality wine is produced from the Vitis Vinifera species which originated in Europe and which dominates commercial wine production. There are thousands of varieties some of which have become better known than others. Famous red wine varieties include Merlot, Cabernet Sauvignon, Pinot Noir, Zinfandel and Shiraz (Syrah). Well known white wine varieties include, Sauvignon Blanc, Chardonnay, Pinot Grigio and Viognier. The variety of grapes grown influences the style and taste of the wine. In Europe, there is a tradition of matching grape varieties to the soil, weather and climate and this is reflected in quality control rules.
2) Soil
The soil plays a major role in agriculture; grape vines like to thrive in poor soils which are well drained. In a poor well drained soil the vine roots are encouraged to penetrate deeply to obtain both water and mineral nutrients. Poor soils reduce the crop yield which is associated with the production of finer quality wines. Richer soils produce higher yields and this is generally associated with lower quality wine. Much research has been made to into the concept of yield versus quality and there is now a modern emphasis on producing high quality grapes from higher yields. It is not only the soil which affect yield but also growing techniques.
The soil is often associated with the style of wine so, for instance, Champagne grapes grow better in chalky soils.
3) Climate
Climate is different to weather. Climate can be defined as the weather conditions averaged over a long period of time. Climate is influenced by latitude and altitude. In general, vines grow best between latitudes 30 and 50 degrees north or south of the equator. Outside of these latitudes the local conditions or micro-climate may allow viticulture. For example, closer to the equator vines can be grown at higher altitudes where the climate is cooler.
Winter should be cold enough to restrict the growth of the vines to rest them. It should produce frosts severe enough to kill insect pests and diseases but not so sever e as to kill the vine itself. There should be sufficient rain to replenish soil moisture.
Spring should be mild to encourage the growth and budding of the vine. There should be sufficient rainfall to replenish the soil’s moisture and water reserves.
The late spring or early summer should be warm to promote the flowering of the vine.
A hot and sunny summer is then needed to promote the development of the grape berry. Light rain is required to swell the growing grape. Sunny conditions are needed in late summer to start the ripening process.
Autumn needs to be sunny and dry to complete the ripening of the grapes.
4) Weather
Local weather conditions can either encourage the good growth of the vines or adversely affect it. Bad weather can either destroy the vines or reduce the size of the crop.
Heavy frost in spring can destroy roots and prevent the budding of the vine.
Hail in late spring and summer can damage young shoots and flowers and in late summer it can damage the developing fruits.
Heavy or prolonged rain in summer can swell the grapes too much and dilute the sugars, flavours and acids in the berries. Heavy or prolonged rain also encourages fungal and mould disease s and slows down late summer ripening.
In autumn, heavy rain delays the ripening of the grapes or delays the harvest. A damp atmosphere also encourages fungal rot
Strong winds can damage the vines when they are flowering or prevent pollination.
It should be noted that the quality of the vintage of a wine is controlled by the weather not the climate. Good weather in all seasons improves the vintage and its wine but bad weather can ruin the quality of the grapes leading to inferior quality wine.
5) Viticulture
The growing methods in the vineyard also have a considerable influence on the quality of the grapes produced. The growing conditions of the grapes are vital to the health of the vine, the quality of the grapes and the control of diseases and pests.
Climate change is now beginning to affect growing conditions in some regions. In Australia drought has lead to changes and advances in irrigation techniques. In Europe, Spain has been affected by drought, in the La Mancha region, and this has lead to changes in the quality control rules to allow irrigation. Climate change may also affect which grapes can be best grown in a region and may prompt further changes to viticulture and changes to the rules in Europe.
Rootstocks
Whilst the actual grapes are produced from the Vitis Vinifera species, the shoots of this vine are grafted onto the roots of American species of vines including: Vitis Berlandieri, Vitis Riparia and Vitis Rupestris,. American rootstocks are resistant to the insect louse Phylloxera Vastatrix which infests vine roots. This louse has spread throughout all vine growing regions of the world. In the late 19th century, this louse almost destroyed viticulture in France and other European countries. Virtually all vines grown throughout the world are European vines grafted onto American rootstocks and this includes the USA. Rootstocks are selected to suit local climate and soil conditions.

Vine Training and Pruning
Vine training and pruning are essential to maintain the origin and health of the grapes. Because European grapes are grafted onto American rootstocks, any shoots produced by the rootstock above the ground must be pruned away to prevent cross-pollination of the grapes and hybridisation. Equally, the canes and shoots of the European vine variety must be prevented from taking root as they are not resistant to the Phylloxera louse and the vines could be destroyed.
Vines are trained in a way which suits the local vineyard conditions, climate and soil. There are two main ways of training the vines:
Cane training where the main horizontal cane is cut off, in winter, to be replaced by a spare cane. Cane trained vines are trellised on wires supported by a frame.
Spur training as often seen on Bush vines. The main canes are not pruned back in the winter. Bush vines are either left un-supported or just supported by a pole. Other forms of spur trained vines are supported on wires and trellises.
There are numerous variations of both types of training and in some European Countries there are rules governing the training methods used.
Vines can be trellised high to avoid ground frosts or trained low to benefit, at night, from heat stored in stones in the soil.
Vine growth is also influenced by the distance between rows of vines and their orientation either to attract sunshine or avoid dampness etc.
Pruning and canopy management also affects the quality of the grapes and the yield, and is adapted to local growing conditions.
The Vineyard year
In winter the vines are allowed to rest. Pruning is used to train the vines and damaged trellises are repaired. The soil is fertilised if necessary. Any grafting is performed in late winter or early spring when the vines begin new growth.
In spring the ground around the vines is ploughed or hoed to aerate the soil. Spraying against pests and disease is started depending on rules. New vines are planted. Vine training and pruning is continued.
In summer, pest and disease control spraying continues according to rules and standards. The canopy is managed by pruning to ensure that vine growth is concentrated on the production of ripe grapes rather than excess leaf cover.
In autumn, the vintage or wine picking takes place. Vines are either hand picked or picked by machine depending on commercial and quality considerations. Some vineyards do not lend themselves to mechanisation because of geography or the spacing of the rows of vines.

Vineyard location
Vineyards need to be located on soil which is conducive to viticulture. The best wines are usually produced from vineyards located on limestone, chalk, gravel, schist, granite or volcanic based soils.
From a weather and climate point of view, the best location for a vineyard is on a slope for good drainage and facing the sun to attract light and heat.
6) Wine pests and Diseases and their Control
Wine pests and diseases create serious problems for the wine grower and must be controlled for economic and quality reasons.
Phylloxera Vastatrix or the Vine louse
This aphid is the most serious vineyard pest and it can only be controlled by using American rootstocks as described before.
Other Insects pests
Other insect pests, such as the grape berry moth, are controlled using insecticides when they become a problem. Organic growers, who are opposed to the use of pesticides, encourage natural insect predators such as ladybirds or predatory wasps.
Downy Mildew
This is caused by the Peronospera mould which thrives in damp conditions and can destroy leaves and grapes. It can be controlled by spraying with either Bordeaux mixture which is a mixture of copper sulphate, lime and water or Copper based sprays. Improved ventilation of the vines helps to prevent the damp conditions which encourage the mould.
Powdery Mildew
Powdery Mildew or Oidium is caused by a fungus which grows in both humid and dry conditions it can affect both the leaves and the grapes. Even a mild case can affect the photosynthesis in the plant leaves. It is controlled by sulphur or fungicides.
Grey Rot
This is caused by the Botrytis Cinerea, this fungus attacks the vine in wet or humid conditions but usually in autumn when the grapes start to ripen. Grey mould covers the leaves and grapes especially white varieties. Bunches of grapes with grey rot can give an unpleasant taste to the wine.
For certain styles of sweet wine, such as Sauternes or Monbazillac and the sweet wines of Germany, grey rot is encouraged, it is then called noble rot. The white grapes are allowed to develop the rot which dries out the grapes and increases the concentration of sugar to make the high quality dessert wines of these regions. Any unpleasant taste is masked by the sweetness of the wine.
7) General Considerations
The climate, weather, grape type, vineyard techniques and pest and disease management are all subjects which can fill many books. In the final analysis, all of these factors combine together to affect the quality of our vines and ultimately our wine.



 
8) Some questions
What direction is it best for a vineyard to face?
What causes powdery mildew?
Between what latitudes are the wine growing regions mainly located?
Name one type of vine training?
What is the definition of climate?
What is the name of a well known red wine grape?
What is the most important insect pest in the vineyard?
Why are European vines grafted onto American rootstocks?
Name a wine which is produced by grapes exposed to Noble Rot?
What can affect the yield of grapes?
Which soil is regarded as best for growing grapes?
What controls the quality of the vintage the weather or the climate?
In what season are vines left to rest?
In what season does the vintage take place?
What affect does strong wind have on the vine?
Why would vines be trellised high above the ground?
What is the name of a well known white grape?
What components of the grape should be well balanced?