WSET Advanced Chapter 2 The Growing Environment AKC2 Flashcards
Climate and Weather
Climate is the pattern of rainfail, temperature and sunlight averaged out over several years, and it can change over decades. Weather is the annual variation in those averages. In Bourdeaux, there is great variation in rainfall from year to year, while in California’s Central Valley, it is always dry and hot.
Vine Temperatures
Ideal average growing temperature is between 16 and 21 Celsius. Vines go dormant at 10C and begin to die over 22C. Temperature dictates which varietals to grow – Riesling thrives in cool locations, while Grenache needs it to be hot.
Temperature’s Affect on Vine Growth
Cooler: Later budburst, shorter growing season for grapes to ripen, flowering and fruit set can be disrupted, higher acid / lower sugar production. Black grapes may produce bitter/astringent flavors. Better for whites.
Factors Affecting Annual Temperature
Latitude: Vines grow between 30 and 50 degrees latitude, North and South of the equator.
Factors Affecting Continentality
The variation between summer and winter temps is mitigated by large bodies of water. Inland areas suffer larger swings. Niagara viticulture would not be possible without Lake Ontario.
Factors Affecting Diurnal Range
Water: Seas and lakes are the biggest factors that limit the temperature change between day and night, but rivers and streams also have an impact.
Importance of Diurnal Range
Cool Nights help the vine rest and extend the growing season. They also help slow the loss of volatile aromas during ripening.
Characteristics of Wines from High and Low Diurnal Range Regions
High Diurnal Range Wines: Fresher and More Aromatic
Winter Freeze
If the temp falls below -20C, vines can be seriously damaged or killed, particularly the Graft Callus. One solution is to bury the callus, or the whole vine.
Spring Frosts
Occur when air below 0C collects at ground level, freezing water vapor and killing newly-burst buds and shoots, impacting yields significantly.
Four Types of Spring Frost Protection
Burners: Generating heat through combustion, creates movement in the air and prevents frost. Smudge pots create smoke that stays on the ground and acts as insulation.
Mild Winters
Mild Winters can prevent vine dormancy, resulting in multiple low-quality crops per year. The vine’s life will be shortened and vineyard pests will multiply year-round.
High Temperature Summers
Accelerate the ripening of grapes, altering the composition of the grape and the style of the wine. There is also drought risk, which would cause the vine to shed leaves and even die.
Sunlight - Importance and Hazards
Importance: Sunlight is needed for photosynthesis, and the more of it there is, the more glucose is generated.Grapes ripen better if exposed to direct sunlight.
Factors Affecting Sunlight
Seas And Lakes: Bodies of water create cloud cover. Landlocked regions are sunnier. Some bodies of water will reflect sunlight.
Coulure
Also called shatter, coulure is a viticultural hazard that is the result of metabolic reactions to weather conditions that causes a failure of grapes to develop after flowering. Coulure is triggered by periods of cold, cloudy, rainy weather or very high out-of-season temperatures. The condition is most often manifested in the spring. Flowers stay closed and are not fertilized. Thus the vines are not pollinated as the grape fails to develop and falls off. Coulure can also cause irregular bunches of grapes which are less compact than normal.
Water
Water is used for photosynthesis, to give rigidity to shoots and leaves, to regulate temperature and to swell grapes. It travels through the vine via transpiration. The amount of water required a vine is determined by the temperature.
Precipitation
The timing and the amount of rainfall is important. Flowering and Fruit Set can be disrupted by heavy rainfall, reducing the number of grapes formed. Damp conditions encourage fungal infections. Pre-Harvest rains cause the grape swelling, diluting the flavors and sometime splitting the berries.
Three Techniques of Irrigation
Drip: Most advanced and expensive, each vine has a computer-controlled dripper dispensing water.
Not Enough Water
Can cause transpiration to stop, photosynthesis to stop, leaves to wilt, grapes to not ripen, and even kill a vine.
Too Much Water
Early, too much vegetative growth causes shading for grapes and grapes won’t ripen. Late, it creates dampness and rot, makes berries burst, leading to fungal and bacterial infection.
Summer Hail
Can damage grapes and the vines themselves. Nets are used to protect vines in Mendoza, and aircrafts and rockets are used to seed storm clouds with chemicals to prevent hail formation.
Climate Classifications
Cool: Avg Growing Season Temp at or Below 16.5C
Continental Climate
Regions with this climate have the greatest difference in temperature between hottest and coldest months. They generally experience short summers with a large, rapid temperature drop in autumn, low rainfall and high sun.
Cool Continental Climate
There is a danger of spring frosts, and low temperatures can affect fruit set, flowering and ripening. Better-suited to varieties that bud late and ripen early. Germany and Champagne are examples.
Moderate Continental
Summers are hot enough to ripen grapes like Cabernet Sauvignon in a relatively short growing season. The high temperatures could require irrigation.
Maritime Climate
Cool-to-moderate temperatures, low continentality, cloudiness, and evenly-spaced, significant rainfall. Spring and Summer rain threaten flowering, fruit set, and grape health at harvest. However, the warmth, for Bourdeaux, this extends the growing season well into autumn.
Mediterranean Climate
Low continentality with warm, dry summers. The dryness and warmth leads to fuller-bodied wines with ripe tannins, high alcohol and low acid. Low rainfall can make healthy grapes but also lead to drought. Examples include the Mediterranean, Coastal California, Chile, South Easter Australia and the Cape Winelands.
Soil Composition
Soil sits on bedrock, and may be CM or 5+M in depth. Soil particle size is critical, as small ones (like Clay) hold water much better than large ones (like Sand).
Humus
Soil element made up of decomposing plant and animal matter, rich in nutrients with excellent water-retention properties.
Soil and Plant Nutrients
The most important elements are Nitrogen, Phosphorous and Potassium. They are dissolved in the soil.
Terroir
The ensemble of environmental influences that give a wine a sense of place. The combined effects of aspect, slope, climate, weather and grape variety.
