WSET Advanced Chapter 2: The Growing Environment AKC2
|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. |
Warmer: Early budburst, longer growing season, accelerated ripening, loss of acidity, ripening of tannins. Better for reds.
|Factors Affecting Annual Temperature||Latitude: Vines grow between 30 and 50 degrees latitude, North and South of the equator. |
Altitude: Temperature drops .6C for every 100M of altitude.
Ocean Currents: Large volumes of warm and cool water affect air temperatures. The Humbolt off Chile and the Benguela off South Africa cool regions, while the Gulf Stream off NW Europe warms it.
Fog: Fog Cools, like in Napa and Casablanca (Chile)
Soil: Dark, rocky and dry soils absorb and radiate heat.
Aspect: Facing the equator gives the most heat, and steeper slopes benefit more.
|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. |
Cloud Cover: Temperatures drop more quickly on clear nights and rise more slowly on cloudy days.
|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. |
Warm Nights accelerate ripening, particularly sugar production.
|Characteristics of Wines from High and Low Diurnal Range Regions|| High Diurnal Range Wines: Fresher and More Aromatic|
Low Diurnal Range Wines: Fuller-Bodied
|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. |
Wind Machines: Large fans that draw warm air from above and moves it to the ground.
Sprinklers: Water sprayed onto vines releases hit as it freezes, protecting the plant.
Vineyard Design: Avoid slopes and depressions, plant on slopes, train vines high.
|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. |
Hazards: Grapes can be sunburned, leading to dark patches, bitterness, and reduced wine quality. Shaded buds are less fruitful. Too much cloud cover can stop ripening, leading to low alcohol levels, unripe flavors and tannins, low yields the next year and may suffer coulure.
|Factors Affecting Sunlight||Seas And Lakes: Bodies of water create cloud cover. Landlocked regions are sunnier. Some bodies of water will reflect sunlight. |
Latitude: Day length during the growing season is longer when the vineyard is further from the equator. Important for Riesling in Germany and Cabernet Sauvignon in Washington State.
Aspect: Steep Slopes and Slope Direction affect sunlight levels. The best is steep slopes facing the equator.
|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. |
Spinklers: Inexpensive and widely-used, they waste a lot of water and create damp conditions. Can be used as frost protection.
Flood: Very cheap, only possible in flat vineyards with lots of water, like Argentina and Chile.
|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|
Moderate: Avg Growing Season Temp at 16.5C-18.5C
Warm: Avg Growing Season Temp at 18.5C-12C
Hot: Avg Growing Season Temp at or Above 21C
|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).|
Ideal soil has few nutrients, is well drained, and is able to store enough water to support the vine during the growing season.
|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. |
Too much nitrogen can result in overgrowth of canopy and too much shading.
Too few nutrients can lead to chlorosis, when the leaves turning yellow and losing chlorophyll, affecting quality and yield. Generally caused by lack of iron in the soil, typical of the limestone in Burgundy, Barolo and Rioja. It can be addressed through lime-resistant rootstock.
|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.|