WSET Level 3 Lecture #2: Natural Factors & Human Influence in the Vineyard (Theory)

This post summarises the theory lecture on 11-Jan-2017, the second of the 15 lectures from WSET Level 3 course which runs from 4-Jan-17 to 19-Apr-17. The tasting part will be covered separately in the next post.

In addition, I inserted relevant YouTube video clips in this post that will help your understanding, especially if you have no background knowledge in viticulture, like me!

1. The Vine 

1.1. Vine species
  1. Eurasian vines (Vitis vinifera): used for fruit production
  2. American vines: used for root stocks (strong resistance to a pest, Phylloxera
1.2. Anatomy of the vine
  1. Green parts: Buds, Tendrils, Leaves, Inflorescences (becomes flower and eventually grapes)
  2. Woody parts: Trunk (permanent wood), Cane (one-year-old wood, last year’s shoots), Shoots (green parts from Buds)
    1. Cane: long one-year-old wood, from last year’s shoots, with 8 to 20 buds
    2. Spur: short one-year-old wood, from last year’s shoots, with 2 to 3 buds
  3. Roots
    1. American vine rootstocks widely used, thanks to their resilience to phylloxera
    2. Grafting is widely used to join the Eurasian vine (cane or spur) to the American vine rootstock

Video: Four Seasons of the Vineyard at Jordan Winery in Sonoma County, California

Video: Vine grafting – Jordan Winery, changing vineyard varietals

 

 

2. The Growing Environment

2.1. What a vine needs
  1. Heat (from sun or reflected from soil or body of water) – factors such as latitude, altitude, ocean currents, fog, soil, aspect, continentality and diurnal range affect the amount of heat available.
  2. Sunlight (essential for photosynthesis) – factors such as latitude, seas and lakes, aspect affect the amount of sunlight available.
  3. Water (essential for photosynthesis and swelling of grapes) – can be supplied via rainfall and/or irrigation
  4. Nutrients (essential for growth and ripening of grapes) – only a small amount needed
  5. CO2 (always in plentiful supply, yet necessary for photosynthesis)
2.2. Natural factors affecting the style, quality and price of wines
  1. Climate 
    1. Classification – defined using the average temperature during the growing season
      • Cool climate: 16.5°C or below
      • Moderate climate: 16.5°C to 18.5°C
      • Warm climate: 18.5°C to 21°C
      • Hot climate: 21°C or above
    2. Typical climate types
      • Continental climate
        • greatest difference in temperature between the hottest and coldest months
        • dry and short summers, large temperature drop in autumn 
        • better suited for varieties that bud late and ripen early
        • Chablis, Champagne, Alsace, etc.
      • Maritime climate
        • cool to moderate temperature, small difference  in temperature between the hottest and coldest months
        • evenly spread rainfall
        • Bordeaux, etc.
      • Mediterranean climate
        • small difference  in temperature between the hottest and coldest months
        • warm and dry summer
        • fuller bodied, riper tannins, higher alcohol and lower acidity
        • coastal California, Chile, South Africa, etc.
  2. Soils
    1. Soil supplies water and nutrients
    2. Stones (for drainage and heat) , sand, clay, humus (like compost)
      • Best soils – well drained, retaining only just enough water
    3. Nutrients (nitrogen, phosphorus, potassium)
      • too much – vigorous growth (no concentration or intensity of the grapes)
      • too little – ill health (chlorosis)
  3. Weather
    1. Temperature hazards (winter freeze lower than -20°C, frost, cold spring, excessive heat, etc.)
    2. Water hazards ((drought, flood, hail, etc.)
    3. Sunlight hazards (too much or too little)
2.3. Human factors affecting the style, quality and price of wines
  1. Viticulture (agriculture, ‘gardening’)
  2. Vinification (making wine, ‘cooking’)
  3. Maturation (what kind of vessel, what kind of processes, for how long)
  4. Marketing

 

3. Vineyard Management

3.1. Site selection
  1. Environment
    1. Temperature, rainfall, sunlight hours, soil, drainage
    2. These factors will influence the choice of grape variety, planting density, systems of training and trellising
  2. Business
    1. Proximity of vineyard to the utility infrastructure, workforce, machinery, cost of land, etc.
  3. Grape variety
    1. It must suit the climatic conditions of the site
    2. There must be a demand for the grapes
    3. Local legal restrictions
3.2. Planting
  1. First yield: normally in the third year after planting
  2. Most vines replaced between ages of 30 to 50 years old
  3. Vineyard land is left fallow for three years or more after vines are dug up
3.3. Managing the vine
  1. Vine training: moulding of the permanent wood and shoots to the desired shape
    1. Head training: relatively little permanent wood left, only hand harvesting possible
    2. Cordon training: ‘cordon’  is a permanent horizontal arm, more permanent wood left and this makes it easier to use machines
  2. Vine pruning: removal of unwanted leaves, shoots or wood, during winter and summer
    1. Winter spur pruning: ‘spur’ is a short one-year-old wood, from last year’s shoots, with 2 to 3 buds.
      • Cordon-trained vine: spurs are distributed along a cordon
      • Head-trained vine (‘bush’ training): spurs are placed around the top of the trunk 
    2. Winter replacement cane pruning (aka ‘Guyot’ training): ‘cane’ is a long one-year-old wood, from last year’s shoots, with 8 to 20 buds
    3. Summer pruning: trimming the canopy to restrict vegetative growth and direct sugar production to grapes
  3. Vine trellising: using stakes and wires to support the trained vine
    1. Untrellised vineyards
      • Head-trained and spur-pruned
      • Suitable for hot, dry, sunny regions with extra shades to protect grapes (Southern Rhône in France or Barossa Valley in Australia)
      • Gobelet in Beaujolais: vines are tied at the tips to expose grapes to air and sunlight
    2. Trellised vineyards
      • Head-trained and replacement cane-pruned
      • Cordon-trained and spur-pruned
      • Requires a line of posts joined by horizontal wires
        • To arrange young shoots to control the amount of air and sunlight
        • To improve air circulation through the leaves and grapes
        • To use machines in the vineyards
      • Vertical Shoot Positioning (VSP): most widely used for both types of pruning
  4. Density: number of vines planted in a given area, expressed as the number of vines planted per hectare
    1. No correlation between density and quality
    2. Water supply: very limited water available – low density (ex. Spain bush vines)
    3. Nutrients:
      • Low nutrients and sufficient rainfall – high density with strict control of the number of buds (ex. Bordeaux) to reduce green vegetative growth and induce competition among vines
      • High nutrients and sufficient rainfall – too fertile soils are not suitable for viticulture, low density with multiple cordons or canes (ex. New world)
  5. Yields: measure of the amount of grapes produced
    1. An estimate can be made from the number of buds left on the vine after winter pruning
    2. No correlation between yield and quality
      • High levels of sunlight / head / nutrient: potential for higher yields of quality fruit
      • Low levels of sunlight / head / nutrient: only potential for lower yields of quality fruit

Video: Seasons of the Vineyard – Jordan Winery, Spring & Summer in the vineyard


 3.4. Pest & diseases
  1. Risks 
    1. Limiting photosysthesis
    2. Damaging or destroying the grapes
    3. Killing the vine
  2. Treatment & management
    1. Rootstocks
    2. Physical barriers
    3. Chemical sprays
    4. Canopy management
  3. Pests
    1. Phylloxera – American vine rootstocks used
    2. Nematodes – sanitising the soil
    3. Birds and mammals – netting or fencing 
    4. Insects – regular spraying or integrated pest management
  4. Fungal diseases (warm, humid and damp conditions)
    1. Downy mildew – copper-based spray (but must stop close to harvest), open vine canopy
    2. Powdery mildew – sulfur-based spray (but must stop close to harvest), open vine canopy 
    3. Grey rot – same fungus resulting the ‘noble rot’ for sweet wines, Botrytis cinerea (if the right conditions are met such as sunlight and dry afternoons)
  5. Other diseases
    1. Viruses – no treatment, only be eradicated by digging up the vines and sanitising the land
    2. Bacterial diseases – spread by small insects such as sharp shooters in California, no treatment, only be eradicated by digging up the vines and sanitising the land
3.5. Viticultural practices
  1. Sustainable agriculture
    1. Chemical usage is restricted
    2. Integrated pest management and biodiversity
  2. Organic agriculture
    1. Only a very limited number of the more traditional treatments against pests and diseases is allowed only in very small quantities
    2. Accreditation is required from an organic certification body
  3. Biodynamic agriculture
    1. Organic practice incorporating philosophy and cosmology
    2. Vineyard soil is seen as part of the connected system with the planet Earth, the air and other planets
    3. Accreditation is required from an organic certification body
3.6. Harvest
  1. Timing
    1. Véraison: point at which the grapes begin to ripen, signalled by a change in colour of the grapes’ skins
    2. Monitoring the rise of in sugar levels in grapes to track the ripening process
    3. The ideal balance among sugar, acid, flavour and tannin is desired, depending on the grape variety, the climate and the style & quality of the wine being produced
    4. Factors to consider:
      • How the vines are planted
      • Labour availability and cost
      • Topography of the vineyard
      • Weather conditions
      • Winemaking choices
  2. Hand harvesting
    1. Advantages
      • Grape selection can take place in the vineyard (by ripeness or quality)
      • Grape stems are retained for the whole bunches
      • Only solution for steep and high quality vineyard (Douro in Portugal, Mosel in Germany or Northern Rhône in France)
      • Only solution for noble rot berries selection
    2. Disadvantages 
      • Labour intensive and expensive
  3. Machine harvesting: works by shaking the trunk of the vine and collecting the ripe grape berries as they fall off 
    1. Advantages
      • Cheaper
      • Speed (especially under bad weather or varieties such as Sauvignon Blanc which over-ripe quickly)
      • Work through night to harvest at lower temperature
    2. Disadvantages 
      • Only be used on flat or gently sloping land
      • Cannot be used for wine styles that require whole bunches of grapes (Beaujolais, Champagne)

Video: Hand harvest vs. Machine Harvest

 

4. My Thoughts

Too much information to digest! Yet, I definitely can appreciate more how difficult it is to cultivate grapes, especially good quality grapes to produce good wines. Hats off to all the grape growers and farmers out there. Thank you for all your hard work!

On the other hand, how am I going to remember all these information for the exams! With a very limited background and no experience on agriculture, it was quite difficult to comprehend this lecture. Those videos were very helpful to visualise and understand the difference training and pruning practices.

2 Comments

  1. JH
    26 Jan 2017

    Thanks for posting videos, I enjoyed watching them, especially the first one!

    Reply
    1. sooh
      31 Jan 2017

      You are welcome!

      Reply

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