Viticulture & Climate

Question 1

What are the 2 main species of grapes used in winemaking? Explain their roles.

Answer 1

1. Vitis vinifera - European species. It is the main species used in winemaking. Susceptible to Phylloxera.
2. American vines - there are 3 important vines native to North America. They are rarely used in winemaking as they produce wines with unattractive flavours. They however are resistant to Phylloxera, and thus widely used as rootstock for grafting of V.vinifera.

Question 2

What are the principal differences between grape varieties?

Answer 2

Grape Colour and Flavour
Budding and Ripening Times
Resistance to Disease

Question 3

How are grape varieties grown and propagated?

Answer 3

This cannot be done via seed.

In order to preserve the unique qualities of a variety, a grower can use one of 2 techniques:

1. Cutting: a section of a vine shoot is taken, planted and grows as a new plant.
2. Layering: This happens in the vineyards. A cane is bent down and a section of it is buried in the soil. The cane tip points upwards out of the ground. The buried section takes root, and once established, the cane linking the new growth to the original plant is cut.

Due to the risk of Phylloxera, most grape growers now use cuttings instead of layering.

Question 4

Explain Clonal Selection

Answer 4

Clonal Selection: vines with positive mutations (e.g. disease resistance, better quality of fruit) are selected for further propagation by cutting or layering

In grape growing, each individual vine or group of vines that show a particular set of unique characteristics is known as a clone. The difference between clones is often small and all of the individual plants that make up a clone would still be considered to be from the same variety.
Some mutations have such significant effects that the same plant are treated as if they are new varieties, even though strictly speaking they are clones of an original plant.
E.g. Pinot Blanc, Pinot Gris are mutations of Pinot Noir

Question 5

What is a Crossing? Name some examples.

Answer 5

Crossings are new varieties produced from 2 parents of same species (i.e. Vitis vinifera)

Cabernet Sauvignon = Cabernet Franc + Sauvignon Blanc
Chardonnay, Aligote, Gamay, Muscadet Melon de Bourgogne, Auxerrois = Pinot Noir x Gouais Blanc
Müller Thurgau = Riesling x Madeleine Royale
Pinotage = Pinot Noir x Cinsault

Question 6

Pinotage is a result of crossing which varieties?

Answer 6

Pinot Noir x Cinsault

Question 7

Müller Thurgau is a result of crossing which varieties?

Answer 7

Riesling x Madeleine Royale

Question 8

Cabernet Sauvignon is the result of crossing which varieties?

Answer 8

Cabernet Franc x Sauvignon Blanc

Question 9

Name five grape varieties that arose from crossing Pinot Noir x Gouais Blanc

Answer 9

Aligote
Auxerrois
Chardonnay
Gamay
Melon de Bourgogne

Question 10

What is a Hybrid? Name an example.

Answer 10

Hybrid is vine whose parents come from 2 different vine species. Typically hybrids have at least 1 American parent vine

E.g. Vidal in Canada

Question 11

Explain the anatomy of 1 year old wood, and permanent wood on a grapevine.

Answer 11

1 year old wood
Shoots turn woody during winter after they have grown; the following spring they become 1 year old wood and buds that formed on them the previous year burst (budburst) and grows into shoots.

Managing 1 year old wood is vital for grape grower as vines normally only produce fruit on shoots that grow from buds that developed the previous year.

Every winter the vine is pruned and one year old wood will either be called:
- Cane: long with 8-20 buds
- Spur: short with 2-3 buds

Permanent Wood
Wood that is >1 year old
Amount of permanent wood is restricted by pruning.
Permanent wood is made out of trunk, and where present, the arms (cordon) of the vine (head if not present)
Not every vine has the same configuration of permanent wood.

Question 12

What feature on American vines confers Phylloxera resistance?

Answer 12

American Vines are able to inhibit the underground louse by:

1. Clogging its mouth with a sticky sap.
2. Forming protective layers behind the feeding wound preventing secondary infections

Question 13

Name 3 regions that are Phylloxera-free.

Answer 13

Chile (isolated by Pacific Oceans on West and Mountains, Dessert on East and North)

South Australia (aggressive quarantine system)

Washington State

Question 14

What is Grafting?

Answer 14

Grafting is the technique used to join a rootstock to a V.vinifera variety.

Rootstocks can provide many other advantages besides resistance to Phylloxera, and a large number of hybrids have been bred accordingly. For example, specific rootstocks can be used to protect against nematodes and provide better resistance to drought conditions.

Question 15

Explain the types of grafting.

Answer 15

1. Bench Grafting
Automated process that is carried out by specialist plant nurseries.
Short section of cane from both the Vitis vinifera variety and the rootstock variety are joined together by machine and stored in a warm environment in order to encourage the two parts to fuse. Once this happens, the vine can be planted.

2. Head Grafting
Usually used when the grape grower with an established vineyard decides to switch to a different grape variety between seasons.
The existing vine is cut back to its trunk, and a bud or cutting of the new variety is grafted onto the trunk.
If the graft is successful, the vine will produce the fruit of the new variety at the next vintage.
It takes a newly planted vine a minimum of 3 years to produce a commercial crop, but this technique can allow the grower to adjust quickly to changes in market demand.
It is considerably cheaper than replanting the whole vineyard and the new variety starts life with an established root system.

Question 16

What is Véraison

Answer 16

During Late Summer/Autumn, grapes start to ripen. They become swollen with water, sugar levels rise and acidity falls. Flavours develop.

Véraison is the process whereby the grape starts to change in colour from green to blue/black, pink or golden depending on variety.

Question 17

What are the essential factors that allow for, and affect viticulture?

Answer 17

Heat (Temperature)
Sunlight (Amount and Intensity)
Water (Rainfall, Irrigation)
Nutrients (Soil and Terroir)
Carbon Dioxide

Question 18

What is the difference between Climate and Weather?

Answer 18

Climate: annual pattern of heat (temperature), sunlight and rainfall averaged out over several years.

Weather: annual variation that happens relative to climatic average.

1. Climate does not vary year on year, though it may change over decades.
2. Climate is affected by a) Latitude, b) Altitude, c) Moderating Influencers e.g. large bodies of water (oceans, seas, lakes, mountains)

Question 19

Explain the factors that determines a region’s Climate.

Answer 19

Climate is the annual pattern of temperature (heat), sunlight and rainfall averaged over few years.

It is affected by the following:

1. Latitude
2. Altitude
3. Moderating Influencers e.g. large bodies of water (oceans, seas, lakes, mountains)

Question 20

Name and Explain the types of Climates.

Answer 20

Climates are described in terms of average temperature over the growing season + variability throughout the year (continentality) or day (diurnal variation)

Temperature:
Cool climate: T below 16.5C
Moderate climate: T 16.5-18.5C
Warm climate T 18.5-21C
Hot climate T above 21C

Continentality/Diurnal Variation
Continental climate:
- Greatest temperature difference between hottest and coldest months
- Usually characterized by hot, short summers with large, rapid temperature drops in Autumn and cold winters

Maritime climate
- Low annual difference between hottest and coldest months
- Rainfall spread evenly throughout year which helps moderate temperature, meaning that temperatures are warm enough for grapes to continue ripening far into Autumn

Mediterranean climate:
- Low annual difference between hottest and coldest months
- Summers tend to be warm and dry; lower rainfall compared to Maritime climates.
- The extra warmth, sunlight compared with maritime climates lead to wines that are fuller bodied, with riper tannins, higher alcohol and lower acidity

Question 21

Explain the main climatic risks of a cool continental climate.

Answer 21

SPRING
Spring Frosts
- Cold spring frost/wind that settles may damage the vine’s new growth, reducing yields
- Young tissues are vulnerable to damage as ice crystals damage plant cells

SUMMER/AUTUMN
Low growing season temperatures
- Inappropriately low growing season temperatures may affect flowering, fruit set and poor ripening.

WINTER
Freezing of vines
- Below temperatures of 15C, permanent wood on the vines may be damaged
- Bark may be split, leading to secondary bacterial infections called crown gall

Cool continental climates are best suited to late budding, early ripening varieties

Question 22

What are the mitigating factors for the viticulture risks in cool continental climates?

Answer 22

SPRING
Spring Frosts (4 main methods)
- Heaters: heat generated creates movements in the air that prevents cold air from settling.
- Wind machines: draws warmer air from above to keep temperatures at ground level before freezing temperatures
- Sprinklers: sprays water on vines. As water freezes, it releases heat into the plant tissue thereby protecting the buds and shoots
- Thoughtful vineyard choice and design: planting vineyards on slopes, to avoid depressions in which cold air can collect. Vineyards near water bodies also mitigates frost as breezes from the water bodies prevent cold air from settling. Vines can also be trained high to avoid the worst of cold air.

SUMMER/AUTUMN
Low growing season temperatures
- Slopes and aspect: steep slopes with aspect facing the equator to maximize sunlight and heat during the day
- Soils: gravel or stony soils that are able to absorb, radiate and reflect heat
- Proximity to water bodies: water body to absorb, radiate and reflect heat

WINTER
Freezing of vines
- Earthing up: earth can be used to bury vines/grafts during the winter.
- Thick geotextiles may be draped over vines
- Wind machines can mix cold and warm air

Lack of Dormancy
- Due to mild (or lack of) winters, the vine will not have a dormant period and produce more than 1 crop per year. This shortens the lifespan and quality of the grapevine.

Cool continental climates are best suited to late budding, early ripening varieties

Question 23

Most grape growing regions are located at what latitude?

Answer 23

30-50 degrees North/South of the Equator

Question 24

What are the climatic influences on Heat?

Answer 24

Latitude
Altitude
Ocean Currents/Sea Breezes
Rivers and Lakes
Air (Warming and Cooling)
Cloud, Fog and Mist
Mountains
Slope and Aspect
Soil

Question 25

Explain the moderating influence of Ocean Currents/Sea Breezes.

Answer 25

Major currents transport large volumes of warm or cold water across the surface of the Ocean, leading to localized warming or cooling in certain regions.

Regions with warm climates that are close to the Sea/Ocean may benefit from cooling Ocean currents. Examples include:
- Benguela Current in South Africa
- Humboldt Current in Chile

Regions with cool climates, close to the Sea/Ocean may benefit from warming Ocean currents. Examples include:
- Gulf Stream in North-Western Europe

Question 26

Explain the differences, and impact of Cloud, Fog and Mist.

Answer 26

They are all water vapour that can be seen in the air.

Clouds form above ground level, and can block sunlight to a vineyard.
- As a result, grapes may take longer to ripen due to lack of sunlight (and thus photosynthesis
- Important moderating influence in warm climates e.g. Hunter Valley or Coonawarra

Fog forms at ground level, and cools down a vineyard that may otherwise be too warm to produce high quality grapes.
- Important moderating influence in warmer, coastal regions e.g. Los Carneros - San Pablo Bay Fog, and Casablanca Valley, Chile

Mist is a less dense form of fog.
- Mist that forms near Rivers during them mornings in Autumn are essential for the development of noble rot.

Question 27

Explain the climatic influence of Mountains, with examples.

Answer 27

Mountains form a physical barrier, sheltering vineyards from clouds, rain and cold winds.
They often result in sunny summers, dry autumns and extended growing seasons.

Examples include:
Vosges Mountains, Alsace
Haardt Mountains (continuation of Vosges), Pflaz, Germany
Cantabrian Mountains, Rioja

Question 28

Explain the influence of Diurnal Range on wine produced.

Answer 28

Diurnal range is the difference between day time and night time temperatures.

Cool nights slow the loss of aromas and acidity (slows respiration of malic acid) during ripening.
Warm nights accelerate ripening.

Hot climates with high diurnal range can produce fresher, more aromatic wines compared to a vineyard with smaller diurnal range.
Cool climates with low diurnal range allows for elongated ripening, and continued degradation of acidity, and methoxypyrazines.
- E.g. Mornington Peninsula in Victoria, Australia; Mosel in Germany

In addition, cool nights encourages formation of anthocyanins that impart colour to the wine.
- E.g. Uco valley in Mendoza, Argentina that produces inky, deeply coloured Malbec.

Question 29

What factors affect Diurnal Variation

Answer 29

Proximity to Water Bodies
A vineyard’s proximity to water bodies (seas, rivers, lakes) can reduce its diurnal range. They provide cooling breezes and absorb heat during the day, and slowly radiate it back out overnight.

Cloud Cover
The level of cloud cover can affect diurnal range. This is because temperatures:
- Drop more quickly on clear nights, when there is no insulating blanket of cloud, increasing the diurnal range.
- Increase more slowly on cloudy days when sunlight cannot heat the ground effectively,

Question 30

What are the risks associated with Drought

Answer 30

Drough is caused by prolonged period of below average rainfall and often made worse with above average temperatures.

Vines are subject to water stress. Photosynthesis is shut down, leaves wilt and grapes fail to ripen.
Ultimately this weakens and kills the vine.

This can be overcome with irrigation, but not always possible due to lack of water, or legal restrictions.

Question 31

What are the risks associated with Rainfall

Answer 31

The effect of rainfall depends on the timing.

Spring/Summer
- Disrupts flowering, leading to Coulure and thus reduced yields
- Leads to poor fruit set, and reduced yields

Summer
- If the vine has too much access to water during the growing season, the vine will continue to grow shoots/leaves instead of focusing on grape ripening
- Extra shoots and leaves increase the amount of shading in canopy, restricting grape ripening
- Waterlogged soils can cause roots to be saturated and die.
- This can be mitigated by planting vines on slopes

Summer/Autumn
- High levels of moisture can promote fungal disease.
- Close to harvest, heavy rainfall can cause grapes to swell and dilute flavors. In extreme cases the berries swell and split, attracting fungal diseases.

Question 32

What are the hazards associated with Sunlight

Answer 32

Poor Sunlight
Sunlight is required for successful flowering and fruit set.
Cloudy conditions can result in smaller crops of grapes + ** slows photosynthesis** and grapes are unable to ripen fully.

Too Much Sunlight
Intensely sunny conditions can cause sunburn, leading to bitter flavors developing in the grape skins.

Canopy management is thus important to maximize sunlight in cloudy areas, or provide shade in hot, sunny regions.

Question 33

What are the methods of Irrigation

Answer 33

1. Drip Irrigation
This is the most advanced but expensive method.
Each vine has its own dripper that can be computer controlled to ensure each vine gets the optimum amount of water.

2. Sprinklers
Still widely used and cheaper than drip irrigation.
However, wastes alot of water and like rain, can create damp conditions in the vineyard and thus higher disease pressure.
If correctly designed, may be used for frost protection

3. Flood Irrigation
Very cheap to use but only possible in vineyards that are flat or very gently sloping, where there is access to large quantities of water.

Question 34

What are the risks associated with Hail

Answer 34

Hail damages the grapes and vines itself.
In worst cases, it can destroy an entire crop.

Question 35

What are the essential nutrients for a vine? What happens if there is insuffient nutrients?

Answer 35

NPK:
Nitrogen
Phosphorus
Potassium

Lack of nutrients can lead to chlorosis.
- Leaves turn yellow and vine’s ability to photosynthesize is restricted
- Grapes struggle to ripen and quality, quantity is reduced

Question 36

Explain Vine Training

Answer 36

Vine training refers to the shape of permanent wood of the vine.

There are two main types of training:

1. Head Training
These vines have relatively little permanent wood.
- Some only have a trunk; others have a few short arms of permanent wood growing from the top of the trunk
- Can be Spur-pruned, or replacement-cane pruned

2. Cordon Training
These vines typically have a trunk withone or more permanent horizontal arms or Cordons.
- Spur-pruned
- Takes longer to establish due to greater amount of permanent wood.
- Study permanent Cordon with shoots positioned along its length allows mechanization in the vineyard e.g. machine harvesting.

Importantly, both can be:
- Low trained, to benefit from heat retained from the soil
- High trained, to avoid frost

Question 37

Explain Vine Pruning

Answer 37

Vine pruning is the removal of unwanted leaves, canes and permanent wood.
- It shapes the vine and limits its size.
- Often takes place during Winter and Summer.

Winter Pruning is important as its main purpose is to determine the number and location of buds for the next growing season.

There are two styles of Winter Pruning:

1. Spur-pruning
Spurs are short sections of 1 year old wood that has been cut down to only 2-3 buds.
The spurs are either distributed along a cordon (arm) or permanent wood (cordon trained), or around the top of the trunk (head trained)

2. Replacement-cane pruning
Also called “Guyot Training”
Canes are longer sections of 1 year old wood and can have anywhere between 8-20 buds.
Typically only 1-2 canes are retained, and each tied horizontally to trellis for support.
This is more commonly seen on Head trained vines.
This is more complex than spur pruning and requires large skilled labour force to choose suitable canes and train them.

Summer Pruning:
Involves trimming canopy to restrict vegetative growth and direct sugar production to the grape.
Also involves leaf stripping so that the bunches of grapes have optimum exposure to sunshine.

Question 38

What are the benefits of Summer Pruning

Answer 38

Summer Pruning:
Involves trimming canopy to restrict vegetative growth and direct sugar production to the grape.
Also involves leaf stripping so that the bunches of grapes have optimum exposure to sunshine.

Question 39

Explain the benefits and disadvantages of Untrellised vines

Answer 39

Untrellised Vineyards
- Vines are not trellished, shoots hang down ooften as far as the ground
- These are called bush vines, and typically head trained, spur-pruned.

Advantages
- Extra shade helps protect grapes from sunburn
- Suited to warm, hot, dry and sunny regions e.g. Southern Rhône, France and Barossa Valley, Australia

Disadvantages
- Shade can impede grape ripening in regions with poor sunlight
- There is less airflow, and this can promote fungal disease.
- This is thus avoided in cool or wet climates e.g. Beaujolais
- In Beaujolais, the shoots of head trained, spur pruned vines are tied together at the tips, to help expose bunches to air and sunlight. This is referred to as Gobelet.
- Untrellised vineyards are also not suitable for mechanical harvesting

Question 40

Explain the benefits and disadvantages of Trellising.

Answer 40

Canopy Management:
Each row of vines requires a line of posts joined by horizontal wires. The vine’s canes and shoots are then tied to the trellis. Together, this is known as canopy management.

Advantages
1. Control Sunlight Exposure
- Arrangement of young shoots can be used to control the amount of sunlight to gets into the canopy
- Maximizes grape exposure to sunlight (and thus ripening) by keeping the shoots apart to create an open canopy in regions with poor sunlight
- Reduce sunburn in regions with intense sunlight

2. Improve Air Circulation
   - Improve air circulation with an open canopy
   - Important in wet climates to prevent diseases
3. Aid Mechanization
   - Positioning grapes in one area of the vine and leaves in another means that mechanical harvesting, spraying of insecticides/fungicides is made more effective

Question 41

What is VSP?

Answer 41

Vertical Shoot Positioning:
System of trellising and canopy management.
Can only be used with replacement cane or spur pruned vines.

The vine’s shoots are trained vertically and tied into place onto the trellis forming a single, narrow canopy.
By keeping the shoots apart, this keeps the canopy as open, well aerated and shade-free as possible.

In hot, sunny regions, VSP can be adapted so that thetops of shoots are not tied in, but flop over creating some shade in the canopy to protect the fruit
- Benefit over Bush Vines: mechanical harvesting is still possible.

Question 42

What are Nematodes?

Answer 42

Nematodes are microscopic worms that
- Attack the root of vines, interfering with water and nutrient uptake.
- Can transmit vine viruses.

Question 43

Explain the effect of Fungal Disease

Answer 43

Downy and Powdery Mildew:
Affects all green parts of the vine including leaves and grapes
Grapes lose their fruity flavors, giving wine a moldy, bitter taint.

Grey/Noble Rot:
Typically attacks grapes.
Can taint grape flavors and lead to color loss in black grapes.