Annual life cycle of the vine

-Weeping (February in the Northern Hemisphere / August in the Southern Hemisphere)
Vine awakens oozing out the cane ends that were pruned in the winter. It is a signal to prune for the spring growth.

-Bud break (March to April NH / September to October SH)
The buds open. Process is slower in clay based soils, which are colder and faster in sand based soils, which are warmer.

-Shoot growth (April to May NH / October to November SH)
Foliage develops and shoots are sent out and tiny green clusters form.

-Flowering (May to June NH / November to December SH)
The tiny green clusters turn into flowers.

-Fruit set (June to July NH / December to January SH)
Each fertilized berry expands into a grape.

-Véraison (August NH / January SH)
The grape develops its fleshy fruit and its skin begins to turn a different colour.

-Harvest (August to October NH / February to April SH)
White grapes ripen before black grapes and must be harvested earlier

-Dormancy (November to February NH / May to August SH)
This period starts with autumn leaf fall. Pruning is carried out when the vine is dormant.

Grape variety
The best vine species for quality wine production is vitis vinifera. Over time, certain varieties have emerged as being capable of consistently producing good or great wines. These are referred to as classic or noble varieties.

The constituents:

Grape juice
-Water 73.5%
-Carbohydrates 25% (5% cellulose 20% sugar)
-Acids 0.8% (0.54% tartaric, 0.25% malic, 0.01% citric)
-Minerals 0.5%
-Tannin and other pigments 0.13%

Wine
-Water 86%
-Alcohol 12%
-Acids 0.4% (0.2% tartaric, 0.15% lactic, 0.5% succinic)
-Carbohydrates 0.2%
-Minerals 0.2%
-Tannin and other pigments 0.1%
-Volatile acids 0.045%
-Esters 0.025%
-Aldehydes 0.004%

Climate
Vines will grow in a wide variety of climates. Vines will not tolerate excessive heat or cold, so most grow in temperate areas. Grapes will not assimilate sugars at temperatures above 30°C and will stop growing at around 8° – 10°C. Vines can tolerate winter temperatures to about -25°C although some are more tolerant than others.

Grapes need a minimum of 1500 hours of sunshine to ripen. They also require at least 700mm of rain. Most vines grow at between 30 and 50 degrees latitude in the Northern and Southern hemisphere. Red grapes need more heat and sunshine than white grapes.

Climate classification systems
European Union wine producing countries are classified in zones from A to C with some subdivisions.

UC Davis developed the Degree Day system of heat summation. A Degree Day refers to “usable heat”. Start of the vine growth typically begins in spring when the average daily temperature reaches 10°C or 50°F. Degree Days measure temperatures over that. The system, which measures usable heat between April 1st and October 31st, was developed in California in the 1940s by Amerine and Winkler. Zones are ranked from 1 – 5 with 1 being the coolest and 5 the hottest. 1, 2 and 3 are considered best for fine wine production and grape varieties were recommended for each zone.

The Heat Summation Scale
Zone 1: less than 2500° F (dry table wines of light to medium body)
Zone 2: 2500 – 3000°F (dry table wines of light to medium body)
Zone 3: 3000 – 3500°F (full bodied dry and sweet wines))
Zone 4: 3500 – 4000°F (fortified wines)
Zone 5: over 4000°F (table grapes and raisins)

Macroclimate
Describes the climate of a large area or region
-Bordeaux: Maritime
-Burgundy: Continental
-Languedoc: Mediterranean

Mesoclimate
Describes the climate of a smaller area: Subregion, group of vineyards, single vineyard. Typically created by surrounding natural features e.g. body of water or a slope. Important in helping determine variety selection for specific areas within a larger region. Also affects vintage quality in small areas.

Microclimate
Describes the smallest unit, down to a single vine or even a space between vines. Can be as small as the climate within a single vine’s canopy.

Annual weather conditions
Yearly variations can be quite significant and these variations are more pronounced in areas of marginal climate e.g. Germany, Champagne and Chablis. Annual weather conditions can be viewed as giving personality to a wine.

Poor weather can cause a number of problems:
Frost in the spring or winter
Spring frost can damage new growth and lead to crop loss. Frost prone sites are best avoided but there are ways of combating it.
-Heaters
-Fans
-Aspersion

Poor weather during flowering
Can lead to two conditions known as coulure and millerandage.
Coulure is a condition where low temperatures and/or wind during flowering cause incomplete fertilization leading to large scale dropping of unfertilized flowers.
Millerandage is the condition that follows where unfertilized flowers stay on the bunch but fail to expand and swell. This leads to irregular ripening and difficulty in determining harvest dates.

Hail
Hailstorms tend to happen early in the growing season and can do a lot of damage but generally in a confined, smaller area. Some growers take out insurance as protection. Nets are also used in some regions e.g. Mendoza. Rockets carrying silver iodide can be fired in the suspected cloud formations causing the ice in the clouds to turn to rain.

Heat stress
Vines stop growing above about 30°C and above 40°C damage will occur. Grapes will start to wither and can suffer “sunburn”.

Soil
Vines will tolerate all sorts of soil types, but with correct preparation, most soils can be made suitable. It is debatable whether specific soil types are more important than the two crucial elements of structure and drainage. Soil drainage is one of the most important features of vineyard soil. Good drainage encourages deep rooting and extraction of deep mineral elements. Fractured bedrock, important in limestone soils, can help with deep rooting, water storage and drainage. The soil type shouldn’t be too permeable or the water will drain away before it can be used. Balance is important.

Heat retention of soil is the rate at which soil warms which has a bearing on fruit maturity: Darker colored soils typically warm up more quickly and store heat better than lighter soils. Rocky soils reflects sunlight to lower leaves and absorbs daytime heat and radiate it at night, important especially in the critical later phases of ripening.

Soil Composition
Soil texture refers to the proportions of different sized particles within it: Sometimes classified in terms of heavy (a high proportion of clay) and light (a high proportion of sand). Texture has a bearing on water retention (heavy vs. light) and soil aeration. Structure is the way the particles are stuck together and is affected by the presence of clay, organic matter and ground chemistry. Both are of importance in that they influence the percolation or drainage of water and also the water retaining properties of the soil and the ability of the roots to penetrate the soil. In general granular structures are preferred because granular soils have roughly 25% coarse material, such as sand, pebbles or rock fragments in their composition. Heavy clay soils tend to encourage shallow rooting, given the available water supply. Soil fertility influences vine growth in particular ways, too fertile a soil will typically encourage vegetative growth at the expense of fruit production especially nitrogen-rich soils. Ideal vineyard soil is at best only when moderately fertile.

Soil Problems
Chlorosis due to lack of iron, is most common in areas where there is high chalk content in the soils. Iron is locked in the soils rather than made available to the plant. Leaves turn yellow and if severe, results in stunted growth and poor yield. Remedy is to increase humus content in the soils, increase the iron content through a soluble spray or use rootstocks that tolerate high chalk content.

Topography
Bodies of water typically present less variation in their internal temperatures than soil. Depending on their volume, they may store considerable heat and moderate cool climates in the winter and moderate hot climates in the summer. Very large bodies of water present specific climatic features such as fog, rain and wind currents. Moderating influence may also be felt during winter dormancy. Mountains can affect rain and wind patterns, water and irrigation, soil depths and ripening periods.

Aspect, slope and altitude
A south or southeast aspect or orientation particularly in the northern hemisphere is preferable. Sloping vineyards in general are considered ideal, the mid-slope is considered finest because it is in this concave section that slope wash is concentrated, good drainage is found and the sun is most felt. The choice to plant at altitude is influenced by the desire to find a suitable mesoclimate in hotter growing regions.

Higher altitudes = Cooler temperatures = Delayed ripening = Extended hang time

Current research also suggests that higher concentrations of UV rays at altitude can stimulate phenolic ripeness.

The Concept of Terroir
Great wines are made up of a multitude of environmental consideration, the French term for this is “terroir”

“The terroir is the coming together of the climate, soil and the landscape. It is the combination of an infinite number of factors: Temperature by night and by day, rainfall distribution, hours of sunlight, slope and drainage to name but a few. All these factors react with each other to form, in each part of the vineyard, what the French call “terroir”” – Bruno Prats of Cos d’Estournel

Viticulture
How the vine is cultivated or managed can have a profound effect on the quality of the fruit it will produce.

The vine
Vitis is the genus – within this genus there are over forty species but only a few are of interest to vine growers, vitis vinifera is the most important. Evolved as a species in what is now Iran but is now considered to be native European.
Vitis labrusca, vitis riparia and vitis rupestris, native North American vine species, are also used.

Development of new varieties

Crossings
New varieties of vitis vinifera are produced by fertilizing the flower of one variety with the pollen of another. This is followed by the planting of the grape seeds that are the product of the cross-pollination. The resulting seedlings are then planted and a rigorous selection of the seedlings takes place based on particular criteria such as disease resistance, vigour, etc… Few new crossings have achieved the prominence of any of the classic varieties although some are important in certain areas.

Hybrids
A hybrid in viticultural terms is the result of pollinating a vitis vinifera vine with an American vine. Originally done due to the fact that some American vines are quite resistant to powdery mildew.

Clonal selection
This is the process where plant breeders select individual vines from an existing grape variety on the basis of certain attributes such as colour, particular flavour, disease resistance, etc… Cuttings are taken and then grafted onto rootstock and planted for further assessment

Vineyard Management
-Planting
-Establishing a new vineyard or replacing old vines
-Preparation of soil
-Selection of vines and rootstock
-Vine density
-Vineyard layout
-Trellising system
-Vineyard Management
-Irrigation
-Pesticide and herbicide use
-Organic and biodynamic viticulture

Irrigation
Less frequently practiced in the Old World but considered essential in many parts of the New World. Banned in most of Europe except for young vines.
-Flood irrigation
-Sprinklers
-Drip irrigation

Pesticides and Herbicides
Pesticides are chemicals that have various levels of toxicity and they are used to prevent, destroy, repel or reduce the harmful effects of fungi, bacteria, insects, nematodes etc… Herbicides are chemicals applied to vineyards to control the growth of weeds and it can be either contact or systemic.

Organic Viticulture
A system of grape growing that does not employ industrially synthesized compounds as additions to the soil or vines to maintain or increase fertility, or to combat pest problems. (1990 US Farm Bill)

Pruning & Training
Reasons for pruning:
-Yield control
-Balancing fruit and vegetative growth
-Set up plant for training system

Factor influencing training methods:
-Climate
-Soil fertility
-Method of harvesting

Various training systems:
-Gobelet (Bush vine) – Spur pruning
-Guyot – Cane pruning
-Cordon – Spur pruning
-Scott Henry – Can be either spur or cane pruning

Yields
An important statistic in wine production, it is the measurement of how much a vineyard produces. Methods of calculating yield:
-Tons/acre
-Hectolitres/hectare
-Pounds or kilos/vine

Dealing with pests
-Pylloxera Vastatrix: grafting
-Grape moths: some moths and caterpillars can damage vines. Early season spraying with pesticides prevents the problems.
-Red and yellow spider mites: Can only be controlled with pesticides.
-Nematodes: microscopic worms that are responsible for a number of disorders. Once infected the vineyard typically has to be ripped out.
-Birds and animals: use of deterrents

Diseases for the vine
-Oidium (powdery mildew)
-Peronospera (downy mildew)
-Botrytis cinerea (noble rot)
-Eutypiose – Eutypa Dieback
-Pierce’s Disease

The harvest
Considerations:
-Picking at the optimum time
-Measurement of sugar
-Balance between sugar and acid
-Flavour development
-Machine vs. hand-harvesting