C4 - The Vine (reviewed) Flashcards
What are the most important species in modern viticulture?
Vitis Vinifera -
- Produces nearly all the grapes used in winemaking
American vines
- widely considered to have unattractive flavours
- but resistant to Phylloxera and consequently widely used to produce rootstocks onto which Vinifera vines are grafted
What factors may a grape grower be concerned with when selecting a grape variety?
- Colour and flavour
- Budding and ripening times
- Resistance to certain diseases
Which two methods may a grower use to preserve the unique qualities of a grape variety? Describe.
Cutting -
- A section of a vine shoot that is planted and then grows as a new plant
- Most commonly used due to the risk of phylloxera
- Usually happens in a nursey
Layering
- A cane is bent down and a section of it is buried in the ground, the cane tip points upwards out of the ground.
- The buried section takes root and when this happens, the linking cane is cut.
- Happens in the vineyard
How can several plants be identified as one variety?
They can all trace their lineage back through a series of cuttings and/or layering to a single plant
What is a Cultivar?
Grape variety or vine variety
Describe clones
- Although the vines of a grapes variety may be the same, some mutations sometimes occur when the vines grow
- Those which have developed positive/beneficial mutations are more likely to be selected for further propagation
- Clonal selection is choosing individual vines with beneficial mutations
- Clonal selection has lead to the development of clones, which is a vine or group of vines that shows a particular set of unique characteristics
- As such grape growers will often specify the clone as well as the variety when ordering new plants
List two varieties which are the result of more extreme mutations from Pinot Noir?
Pinot Gris and Pinot Blanc
What is cross-fertilisation? Describe it.
Cross-fertilisation is a method of creating a new variety under controlled conditions
- Pollen from the male part of the flower of one Vine is transferred to the female part of the flower of another vine and fertilisation occurs.
- The pollinated flowers develops into a grape with seeds.
- If the seed is planted and grows, it will be a new variety.
Why is it costly and time-consuming to create a new variety?
A grape’s characteristics cannot be predicted when cross fertilisation happens occurs, therefore it is costly and time-consuming to create a new variety
- Hundreds of seeds are required
- Many seedlings fail in the first year
- Producers must wait 2-3 years before the survivors flower and produce fruit
- It takes longer to prove the long term value of the new varitey
=> only a few newly bred varieties have found a successful niche over the last 150 years
What is a crossing? What is a hybrid?
Crossing:
- A new variety which is produced from two parents of the same species
- Example: Cabernet Sauvignon (Cab Franc x Sauvignon Blanc)
Hybrid
- A vine whose parents come from two different vine species
What are hybrids and American vine crossings most commonly used for?
Rootstocks
Describe Phylloxera
- Insect native to North America and to which V. Vinifera is unable to defend itself against
- Phylloxera cause the wholesale destruction of European vineyards in the 19th century when it was accidentally introduced
- Strict quarantine procedures have successfully protected Chile, parts of Argentina and South Australia
- American species or hybrids are the only protection against Phylloxera and the only solution when it first hit Europe was to plant American species or hybrids.
- The better, but more expensive solution to Phylloxera which was found at the end of the 19th century was to use the American vines/hybrids as rootstocks to get protection Phylloxera and the flavours of the Vitis Vinfera
How do American varieties protect themselves against Phylloxera?
Phylloxera has a very complex lifecycle and it is most harmful to the vine when it lives underground and feeds on the roots of the vine.
The infection enters through the feeding wound, weakening and eventually killing the vine.
American varieties clog the aphid’s mouth with a sticky sap and form a protective layer behind the feeding wounds to prevent secondary infection
Give two other advantages to some rootstocks other than resistance to Phylloxera
- Protection against Nematodes
- Drought resistance
What is grafting? Describe.
Grafting is the technique used to join a rootstock to a Vinifera variety
Bench grafting (most popular modern):
Short sections of cane from both varieties are joined together by machine and stored in a warm environment to encourage fusion
Head grafting (less common):
- Used when a grape grower with an established vineyard decides to switch to different variety between seasons
- The existing vine is cut back to its trunk
- A bud or cutting of the new variety is grafted onto the trunk
- Advantages: faster and cheaper: the new variety will grow in the forthcoming season (much quicker) and it is much cheaper than replanting a whole vineyard
