THE VINEYARD

Site selection
Before a vine is even planted, the choice of site for the vineyard is crucial. In addition to the factors detailed previously (under site and topography), such as avoiding frosts and guaranteeing good drainage-there are economic factors to consider. Can a vineyard be harvested mechanically? Is there ready access to a market; or, if a cellar door is planned, will there be substantial passing trade? What does the land cost? In Champagne, for example, you will pay much more per acre than you would in Languedoc.

These factors have little importance in the classic regions of Europe. Here, vineyards have been planted for centuries-even millennia-and inherited land is the rule. But elsewhere in the world, including the distant reaches of the south of France or Spain and parts of Eastern Europe, site selection for enterprising new grape growers is very relevant.

Many tests can be done before planting-for instance, to assess drainage, pH and nutrient content. When the tests are completed the land can be prepared-this might be deep ploughing to break up the soil, digging in lime or having the land treated for nematodes or other pests.

Rootstocks
In Europe and California, and often in other parts of the world, grapevines will invariably be grafted on to other rootstocks before planting. The technique of grafting has been known to horticulturists for centuries, and essentially is the insertion of the shoot of one species into the branch of another. This can be done to allow, for instance, two or three varieties of apple to grow out of one tree trunk. In viticulture, it allows shoots from Vinifera vines to be grafted onto the roots of another vine species, often in order to gain resistance to pests, disease or other conditions.

The main reason for grafting in viticulture is to avoid phylloxera (see below), but rootstocks can also benefit vines planted in soils with a high lime content by minimizing the effect of lime in inhibiting the uptake of some essential elements. Other rootstocks can help the vine to cope with summer aridity or high salinity.

Planting
The orientation within which vines will be planted is done with two-sometimes contradictory-aims. The first is to optimize the angle to sun; to be at 90' to the midday sun is generally considered to be ideal. However, it is also better to plant along a slope rather than down it, as rows of vines down a slope will facilitate erosion.
In Europe, vines are traditionally close-spaced, sometimes as many as 20,000 per acre (10,000 per ha). The theory is that this increases the pressure on the vines, limiting yields, and thus guaranteeing quality. In practice, much less dense planting is used in many regions, especially where machines are used for harvesting and other forms of vineyard management. It is also the case that, while dense planting is preferable in the poor vineyard soils of Europe, wider spacing will, in fact, induce the vine to give its best in high-potential soils.

Pruning and training
Pruning allows the viticulturist to determine how productive the vine is to be for the next season, offering the opportunity for a greater or lesser yield. It is also the precursor to training the vine, creating the "architecture" of the canopy to allow for various forms of management.

Training determines how the vine is to be shaped. It may be along a wire, with just one cane or cordon or a number of them, or it may be in bush form, which is excellent for conserving the vine's resources in arid regions, but not a good shape for a vineyard that is mechanized. Canopy management techniques are designed to open grapes up to sunlight, or to encourage airflow to inhibit diseases that stem from humidity.

Irrigation
As with the subject of terroir, irrigation is now very much a non-issue, despite the traditional resistance to it in Europe. Opponents of irrigation would argue the dangers of increasing yield excessively by using extra water, but supporters are aware that it needs to be controlled carefully according to the style of wine being made. It is also worth remembering that the regions in which irrigation is banned tend to be those with a temperate climate and regular, year-round rainfall. Much high-quality Australian and Chilean wine would not exist substantially without irrigation. Interestingly, Spain has now relaxed its ban on irrigation, and the practice appears in other parts of the European Union.

The oldest method of irrigation, known since ancient times, was flood irrigation, which was later developed into irrigation by furrow, channeling water along rows by the vines. This system needs flattish land to work effectively, and vineyards are more often planted on slopes. Spray irrigation was developed over the last 40 years (often with mobile sprinklers), and then drip irrigation, with a pipe along each row of vines

dropping water into the soil, was introduced. The advantages of this system are precision, simplicity and the ability to apply other products such as liquid fertilizer along with the water. It is very responsive, and can be used to a greater or lesser extent according to need.

Many grape growers-especially those committed to quality-would argue that they only resort to irrigation in the driest seasons, except in the first three years of the vine's life, when it is essential to establish the young plant. However, it remains a useful tool in the viticultural armory.

Soil management
Historically, the land between vine rows has been kept free of vegetation. This was useful in dry climates where grass and weeds would otherwise compete with the vines for limited water supplies. However, it has been found that a mid-row crop inhibits soil erosion and makes it easier to get mechanical access without churning up the soil. Careful choice of the crop (grass, clover or rye) allows cutting or digging-in the greenery to create a nutritious mulch. This is more natural than inorganic fertilizers, which are still widely used. Soil compacts with time, so it may be necessary to plough or even deep-rip it to facilitate airflow and drainage. Unfortunately, loosening the soil can also promote erosion.

Diseases and disorders
Much of the viticulturist's time is spent ensuring the good health of the vine. Four types of disease, as well as some disorders, can affect grape vines. The largest group, fungal disease, is caused by microscopic filament-shaped organisms. They include rots, oidium and peronospera

Rots (especially gray rot) attack the whole vine and spread rapidly. Rot starts from dead material (often dead flowers from late spring) and needs humidity to develop. It reduces yields and can impair the color and flavor of wine. It spreads particularly fast when berries are split, which may result from bird activity or rapid berry growth after high autumn rainfall. It is controlled by sprays and preempted by good canopy management. Oidium is a powdery mildew that splits berries and inhibits bunch growth. Uniquely for fungal diseases, it does not need humidity, just warmth and shade. It is now easily inhibited by dusting with sulfur if caught early. Peronospera is a downy mildew that requires warm, humid conditions. A cottony growth appears on the underside of leaves and inhibits plant growth. It is easily controlled with copper-based sprays.

Bacterial diseases are few in number. The most virulent is Pierce's Disease, which kills vines and is incurable, and is a particular problem in the USA. Leaves develop dead spots, which enlarge, causing leaf fall. It is spread by small insects called leafhoppers and occurs especially in vineyards near streams (the bacteria grow in water).

Viral diseases, including fanleaf virus and leafroll virus, are of recent origin (from about 1890) when rootstocks began to be used. They tend to be spread by cuttings from infected plants, although insects like nematodes may pass them on. They do not necessarily kill, but may weaken vines and reduce yields. The only effective treatment is to heat-treat vine stock to create virus-free material. Fanleaf virus, which may be spread by nematodes, causes malformed growth in the form of fan-like deformed leaves that cause poor set and small bunches. Cabernet sauvignon vines are particularly sensitive to this disease. It is a major problem in the Napa valley and Burgundy. So far, the only cure that has been discovered is to uproot the whole vineyard, fumigate and replant it with virus-free stock. With the onset of leafroll virus, often spread by mealy bugs, leaves roll downwards and discolor. It is now widespread, especially in humid regions. Although it rarely kills vines, it reduces yields and delays ripening.

Vine disorders, including chlorosis, couture and millerandage, also occur. These are not diseases, but environmental problems that can afflict vines. Chlorosis is common in chalky soils which inhibit iron uptake from the soil and limit the development of chlorophyll, causing yellowing leaves and poor photosynthesis. Coulure and millerandge refer to poor berry formation resulting from inadequate fertilization of flowers or poor fruit set. It results from poor carbohydrate supply due to inadequate photosynthesis at flowering, usually because of poor weather.

Vine pests
Vines are vulnerable to many animal and insect pests. Birds pick holes in fruit, rabbits and deer nibble shoots, and insects defoliate or attack berries and roots. Critically, pests can also act as vectors, or carriers, of a disease. Different pests are active in different countries and regions, but the one with a worldwide impact on the wine industry is phylloxera.

This small louse, native to North America, lives on the roots of American vine species. Here, vines have become tolerant to the insect and, as it feeds off the roots, they callous over with no lasting damage. However, in other parts of the world vines have no natural protection against this pest and it has caused great destruction.

Phylloxera spread to France in the early 1860s, probably from an imported vine from North America, starting in a vineyard in Marseilles. in searching for food, the American parasite had discovered Vinifera vines and started feeding from their roots. Its life-cycle-a single female can lay up to 20 million eggs in a season-was enough to ensure a rapid progress throughout the entire country (it had reached all parts within 30 years) and then on through Europe.

The French puzzled for years about how to deal with it. They discovered that phylloxera would not tolerate sandy soil, but in practical terms this knowledge was of little use. It could be dealt with by flooding a vineyard for 100 days, but again, that was rarely possible or practical. Certain chemicals injected into the soil would kill it-carbon disulfide was found to be the bestbut they were expensive, dangerous and had only temporary impact. The solution was to graft scions of Vitis vinifera varieties onto rootstocks from Native American vines. That way, growers were able to keep their syrah or Chardonnay grapes but could now protect them from devastation.

In the interim, however, hundreds of thousands of acres of vine had been lost, never to be replanted, and the viticultural map of Europe changed. Old, often high-quality varieties, like carmenere in Bordeaux, disappeared because they could be replanted with more productive vines. Rigorous vineyard management also became the order of the day. Phylloxera still exerts an influence in some regions of the world. It is active in New Zealand and in Victoria in Australia, though other parts of Australia are effectively quarantined. Paradoxically, it has also just run through the vineyards of California, causing complete replanting there.

Age of vines
As each viticulturist has decisions to make about the start of a vineyard's life, so he or she must determine when it should come to an end. Vines reach maximum productivity at about seven years. Productivity declines after 20 to 30 years. Regular replanting is necessary to maintain the yields for those making a mass produced wine from high yields. On the other hand, a producer seeking high quality may welcome the lower yields of older vines, which offer more concentrated flavor and more depth in the resulting wine. In that case, they are more likely to just replace vines as they die rather than replant an entire vineyard, thus maintaining a high average age for the vineyard as a whole.

In some cases, the use of old vines (veilles vignes) is treated as a useful marketing tool. Chateau Tahbilk in Australia makes great play of their shiraz vineyard, planted in the 1860s and used to make a single special wine. With one grape variety, at least, old vines become essential. Carignan, in the south of France, makes undistinguished high-volume wine; however, occasionally, when the vines are allowed to age to 60 or 80 years and the yields drop, it can provide wine of interest and complexity.