SUMMARY
WSET4: D1
WINE PRODUCTION
Iwan Wiering RV, 2023
www.wijnlerendrinken.nl
, Iwan Wiering RV, Summary WSET4 D1: Wine Production, 2023
Summary WSET4 D1: Wine Production
1: The Anatomy of the Vine
Anatomy of the vine
Main shoots, one-year-old wood (=cane), permanent wood, roots
Components of the grape
Water, sugar, acids, colour, tannin, aroma compounds, aroma precursors
Vine’s needs
Warmth, sunlight, water, nutrients, carbon dioxide
Growth cycle
Dormancy, budburst, shoot and leaf growth, flowering, fruit set, grape berry formation, véraison,
ripening, extra-ripening
All vines have 4 sections: shoots, one-year-old wood, permanent wood, roots.
Canopy contains: shoots, buds, leaves, lateral shoots, tendrils, inflorescences/grape bunches.
Compound buds (latent buds): form in one growing season (develop best at minimum 25°C/77°F),
break open and produce shoots in the next growing season.
Prompt buds: form and break open in the same growing season and produce lateral shoots.
In late summer the green shoots lignify (become woody and rigid). These are then described as
canes. In autumn, leaves fall, carbohydrate reserves (koolhydraten, suikers) are laid down in roots,
trunk and branches, and vine enters dormant period.
Lateral shoots: may be removed in summer pruning. They often produce second crop: may be
removed by green harvesting.
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,Iwan Wiering RV, Summary WSET4 D1: Wine Production, 2023
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, Iwan Wiering RV, Summary WSET4 D1: Wine Production, 2023
Water stress closes stomata: limits the intake of carbon dioxide (needed for photosynthesis) and thus
photosynthesis.
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, Iwan Wiering RV, Summary WSET4 D1: Wine Production, 2023
1.2 Vine Propagation
Vines propagated by cuttings (stekjes) or layering (afleggers).
Cuttings: by far most common: treatment in nurseries, use of grafting on rootstock.
Layering (marcottage): only to fill a gap in the vineyard, own roots.
Mass selection: cultivate cuttings
Clonal selection: best performing vine selected to cultivate cuttings. One clone vine.
New grape varieties: cross fertilization (cross, hybrid)
Clonal selection: taking a cutting from a single parent plant and propagating vegetatively over time
to create a new plant that is genetically identical to the parent.
Advantages:
• Management of the vineyard may be easier if the vines ripen at a similar time.
• Clonal selection checks vines for viruses, so vines are virus free
Disadvantages:
• Reduces diversity in vineyard and in fruit which may produce wines that are less complex.
• The same plant in one area could lead to high disease pressure as there may be no or little
resistance to certain diseases or pests.
Mass selection: taking cuttings from certain vines that display desired characteristics which can
include high quality fruit, high disease resistance, etc. Process takes many years as monitoring of how
the vine grows and wines produced from the grapes are assessed until the vines produce what the
grower is looking for.
Advantages:
• Increases diversity in vineyard and potential wines due to plants coming from growers' own
vineyard.
Disadvantages:
• Costly and time consuming to produce a new plant.
• New plant is not guaranteed virus free (viruses parent vine likely to be passed on to new
plant).
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, Iwan Wiering RV, Summary WSET4 D1: Wine Production, 2023
2: The Vine Growth Cycle:
Chapter 04 The life cycle of the vine - YouTube
2.1 Dormancy
November–March (Northern Hemisphere), May–September (Southern Hemisphere)
Dormancy occurs when average temperatures fall below 10°C (50°C). If temperature does not fall
sufficiently to bring on dormancy, the vine will continue to grow and produce a second crop as
happens in tropical climates. If temperature falls below -20°C (-4°F) vines can be seriously damaged or
killed but if temperature drops below -25°C (-13°F), most Vitis vinifera will die. Different grape
varieties have different temperature tolerances and some hybrids have been bred to withstand winter
cold e.g. Vidal.
Winter pruning (pruning later can postpone budburst)
Without leaves no photosynthesis.
Vine needs:
• Temperatures below 10°C (50°)
Adverse conditions:
• Extremely cold temperatures (severe damage below −20°C (–4°F), kill below −25°C (−13°F).
E.g. New York Finger Lakes, Canada, China.
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, Iwan Wiering RV, Summary WSET4 D1: Wine Production, 2023
• Unusually mild temperatures (early budburst). E.g. Lanzarote.
In winter hillsides can be up to 5°C (9°F) warmer than the valley floor.
2.2 Budburst (budbreak)
March–April (Northern Hemisphere), September–October (Southern Hemisphere)
Budburst is when buds swell and open after winter dormancy. Average temperatures above 10°C
(50°C) required for budburst to occur. However, some varieties burst just below 10°C (50°C) (early
budding varieties, more risk of spring frosts, e.g. Merlot, Chardonnay, Pinot Noir, Grenache) and some
varieties require slightly higher temperatures (late budding varieties, less risk of spring frosts, e.g.
Cabernet Sauvignon, Ugni Blanc, Sauvignon Blanc, Syrah). If temperature fluctuates, budburst will be
uneven.
Buds swell and open. More successful (uniform) in continental climates. Winter pruning late can
postpone budburst. Budding late: less risk of spring frosts.
Vine needs:
• Average air and soil temperatures above 10°C (50°F)
Adverse conditions:
• Frost
• Cold soils (clay)
2.3 Shoot and Leaf Growth
March–July (Northern Hemisphere), September–January (Southern Hemisphere)
Shoot and leaf growth has an optimum temperature of approximately 18-33°C (64-91°F) which is not
usually a limiting factor at this time of year.
Vine needs:
• Stored Carbohydrates (starch = zetmeel)
• Warmth (18-33°C (64-91°F) ideal for shoot growth), sunlight, nutrients (principally NPK:
nitrogen, phosphorus, potassium: stikstof, fosfor, kalium) and water
Adverse conditions:
• Low carbohydrate levels (caused by conditions in the previous growing season)
• Water stress (can limit photosynthesis and shoot growth)
Carbohydrates levels can be low in the vine due to the previous year's cultural manipulations
including excessive leaf removal. Leaves are a source of carbohydrates, therefore this canopy
management technique needs to be clearly understood by the grower before being carried out so as
not to unnecessarily deplete the vine.
Cropping the vine very heavily can use up some of the carbohydrates stored in the trunk and roots
leaving less available in the following growing season and weakening the vine in the longer term.
Water stress has a major impact on photosynthesis, a lack of water will result in stomata closing to
preserve water in the vine. This will affect carbon dioxide not being able to enter the plant and
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