NH - Unit 2 - The Vine - Varietal selection and propagation Flashcards
Where can 19th century vines be found that still produce high quality grapes?
South Australia, California
When selectiing vines, the main criteria used are :
- Climate adaptation - cold, short growing seasons, drought etc.
- Resistance to disease - phylloxera, nematodes, mildews, oidium, botrytis
- Adaptation to soil conditions (either ungrafted or grafted vines w/rootstocks) - lime, drought, acidity, salt
- Economic characteristics - high yield, high quality, ability to mechanise
Where did the original cultivated vine ,vitis vinfera sativa, originate?
why?
- transcaucasia
- it had functional hermaphrodite flowers => better yields
Vine hybridisation
- The crossing of V. Vinifera with other Vitis species.
- With the spread of phylloxera, hybrid rootstock were created to make the most out of rootstock.
- Widely used in eastern USA still due to winter cold resistance.
Where did vine hybridisation by grafting between different species begin?
Why?
How?
- In the Europe in the late 19th century
- because the vinifera rootstock was not intolerant for phylloxera
- nurseries developped a large number of hybrid rootstock by crossing V. berlandieri (high calcium tolerance) with V.ripiera and V. rupestris (phylloxera resistant, graft well)
Where did vine hybridisation by interbreeding between different species begin?
Why?
How?
- In the USA
- early setters found that condidions fo V.F. were unsuitable
- they were able to interbreed with indigenous species such as V. Riparia, V. labrusca, V. aestivalis
Why did Europe abandon the productiion of wine from interspecific hybrids?
- the downy-mildew resistant hybrids that were created sinds the introduction of this disease, imported from USA in 1878, produced good yields, had some mildew resistance and some could be planted unfrafted so the became very popular. e.g. 1950 hybrids occupied 30% of French vineyards.
- => sever overproduction problems of poor quality wine
What is special about Regent?
- It is a hybrid
- the 6th most planted grape in Germany
Why are hybrids still used widely in eastern USA?
Due to their high winter cold resisitance.
What are intraspecific vinifera crosses?
Give 2 examples :
The crossing of two vinifera varieties to create entirely new varieties.
e.g Aramon x Teinturier = Petit Bouschet,
Riesling x Madeleine Royal = Müller-Thurgau
What are “teinturiers”?
A grape variety that accumulates anthocyanins in the pulp as well as in the skin, which gives a deep red juice on pressing.
Used by Louis Bouschet for his crossing “Petit Bouschet” (Aramon x Teinturier)
Later further crossed by his son Henri Bouschet for his crossing Alicante Bouschet (Petit Bouschet x Grenache)
What is mass selection?
- The traditional method for selecting vines in which only the desirable plants are selected from which to take cuttings => done by passing trough the vineyard before harvest
- Best done in poor years - can eliminate stock rather than select.
What is clonal Selection, when first carried out?
- plants originated from a single parent.
- propagated vegetivaly => usually by cuttings
- genatically identical
- first carried out on Silvaner (Froelich in 1876)
- up untill 1950’s only in Germany
- now worldwide
Clonal selection criteria
• Yield
- bud fertility, size of berries, success of berry set
- Sugar & acidity concentrations
- Quality of phenolic & aroma compounds
- Resistance to disease, cold & drought
- Freedom from viral infections (fan-leaf, leaf-roll, fleck, vein necrosis, corky bark, stem pitting)
- Ease of grafting
- Cost
How is clonal selection carried out?
- Cuttings are taken from just a few vines from carefully monitored mass-selected vineyards.
- Propagated in controlled conditions, carefully selected.
- Growers plant rather fewer than 10 clones of a variety than poly-clonal populations
Disadvantages of clonal selection
- Closely related vines in the same area will allow for easy spread of disease.
- Some clones are very specialised and only suitable for certain regions/styles of wine.
- Clonal selection has led to in increase in yield, leading to overproduction.
- Led to reduction in vine genetic resources.
What is genetic modification?
- The transfer of genes from one organism to another
- the modification of genes within an organism
Explain the use of genetically-modified vines in commercial vineyards.
- No genetically-modified vines are currently available for use in commercial vineyards.
- Research into improving disease resistance occurs in viticultural research institutes
Why are vines not often planted as seeds?
- propagation from cuttings is quicker and easier
- allows for grafting on the phylloxera-resistent rootstock
- it is difficult to predict the characteristics of plants grown from seeds (unless controlled pollination techniques have been used)
What is the advantage of vine nurseries?
- the possibility of testing plant material prio to sale.
What is layering?
- Vine canes are buried in the ground then separated from the parent plant once they have established their own root.
- Now rare
- only used where phyllexera presents no risks
- used in old vineyards in Argentina
- for Bollinger’s “Vieilles Vignes Françaises” (famously and exeptionally in Champagne)
- the best way to propogate vitis berlandieri and rotundifolia (difficult to root from cuttings)
What do growers who don’t use nurseries tend tot use?
- mass selection (common practise)
- layering (now rare)
What are cuttings?
Pieces of parent plant (stems, roots, leaves) that develop into a new plant when placed in right conditions
What part of vine is used for cuttings?
hardwood winter cuttings from canes
Softwood cuttings are used for :
- research
- however more difficult to propagate
- => available all year round.
Hardwood cuttings should be:
- collected in autumn or early winter when they have optimum carbohydrate reserves.
- from well-ripened and healthy wood, and have plenty of sap, wood firm and free from dark specks
How are cuttings treated?
Stored at 5ºC prior to grafting.
- Heat-treated at 50ºC for 30 minutes, to get rid of pests like phylloxera, nematodes, phytoplasmas.
- need temperatures of 15 - 25ºC, and plenty of water in well-drained soil.
What happens with cuttings that are not grafted?
- they can be planted
- straight away into a nursery
- into a pot in a greenhouse
What do cuttings need to grow successfully?
- plenty of water
- as leaves grow faster than roots
- mist propagation of propagating frame recommended
- warmth
- temperatures of 15 - 25°C
- best heat from below
- loose, well-drained soil in nursery or well aerated potting compost
- also high water-holding capacity
- good drainage
- protection from vine weevils
What are the advantages of grafting the cuttings?
- grafting on American rootstocks to confer resistance to phylloxera or nematodes
- can allow the roots to be better adapted to soil conditions
- grower can better control the vigour of the plant
- selecting low of high-vigour rootstocks
What is the difference between bench- and field grafting?
Bench grafting => indoors
field grafting => outdoors
Explain bench grafting :
- late winter / early spring
- prior to grafting
- scion and rootstock cuttings are stored in damp sawdust => soaked for 24 - 48 hours
- machine grafting
- scion quickly dipped in molten paraffin to just below graft union
- prevent graft from drying out
- grafted cuttings stored in crates containing sand and sawdust
- humidity at 90%
- temp 21 - 29°C for 3 - 5 weeks
- scion and rootstock join together at the graft union with a “callus” of cells
- Callusing complete?
- remove from crates
- trimmed (remove roots from scion, shoots from rootstock)
- redipped in molten paraffin wax
- transferred to
- cold store (1 - 4°C°) => vine nursery
- pots at 18 - 21°C for 7 - 10 days => temperate greenhouse => can be planted within 10 months of grafting
What is top or head grafting?
- to change cultivars in established vineyard
- chip-budding and t-budding : (common)
- bud of new varietal inserted on trunk of old one.
- cleft-budding (less common)
- sawing trunk of the vine
- splitting it vertically
- inserting canes of the new variety into the cleft
- require
- scion cuttings must be collected in winter
- cuttings must be stored low temp and high humidity
- almost complete decapitation of old plant
- works well on young vines
- aftercare is very important
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Explain the species Vitis Vinifera
- Only vine species to survive the quarternary ice ages in Europe.
- Variable vigour and ripening period.
- Adaptable to many soil types.
- Not resistant to phylloxera.
- Not resistant to nematodes.
- 2 subspecies
- V. Vinifera Sativa which is the cultivated vine,
- V. Vinifera Silvestris which is the ancestor of all grape varieties, not hermaphroditic, and almost all eliminated by phylloxera.
Explain V. Vinifera Sativa
the cultivated vine
5 - 10 000 wine producing varieties
selected to be hermaphroditic for good fruit set and relatively large fruit
Explain V. Vinifera Silvestris
- the ancestor of all grape varieties
- not hermaphroditic, and almost all eliminated by phylloxera.
- wild European vines
Explain vitis labrusca
- Found in N.E USA.
- Strong, dark berries, “foxy” aroma.
- Not often used as a rootstock parent.
- common parent in American hybrids as Concord
Explain Vitis riparia
- Found mainly wild on river banks in central-eastern North America.
- used as a rootstock
- Rootstocks low in vigour and surface rooting.
- Encourage early ripening.
- Good phylloxera resistance.
- Suffer from iron deficiency (chlorosis) in chalky soils.
- Used to control vigour on fertile soils.
prefers humid, cool, fertile soils
explain Vitis rupestris
- wild growing on light soils in south-central USA.
- Used primarily as rootstock.
- Vigorous, with a deep rooting system.
- Good resistance to phylloxera.
- Susceptible to iron deficiency (chlorosis).
- Used for poor soils with limited water.
prefers : Deep, poor, healthy soils
explain Vitis berlandieri
- Grown on chalky soils in south USA and Mexico.
- Vigorous and deep-rooting.
- High resistance to chlorosis.
- Cuttings have poor rooting ability.
- Hybridised with riparia and rupestris.
=> Lime-resistant rootstocks that root easily; variable vigour.
What is the cost of a grafted vine?
4 tot 5 times the cost of an ungrafted cutting
Why do they us rootstocks in areas that are unaffected by phylloxera?
Adjusting yield, vigour and ripening times
Phylloxera Vastatrix
- A louse that was accidentally introduced from the USA in 1863.
- Destroyed 2/3rds of European vineyards late 19th century
- Vines die of drought in patches that increase in size year on year.
- Roots of infected vines covered with insects - oval yellow-brown dots surrounded by lemon-yellow eggs.
- Pale green leaf galls on underside on leaves.
- Nodosities (whitish or yellowish growths) near the root tip and tuberosities (swellings) on older roots.
Why are American vine species resistant to Phylloxera?
They form hard, corky layers in the roots beneath the feeding wound of the phylloxera,
- making it harder for the louse to feed
- preventing the invasion by other microbes : bacterias and yeast
How can one prevent distruction by phylloxera?
- Grafting vitis vinifera on rootstocks of American vine species (discovered by Laliman
- growing on sandy soils
- flooding the vineyard 40 days a year
What are nematodes?
Tiny roundworms.
- Common, too small to see with naked eye.
- Pratylenchus and Meloidogyne can damage whilst feeding off roots.
- Xiphinema Index can transmit viral diseases.
What rootstocks are chosen for tolerance to lime?
- vitis vinifera => lime-tolerant
- vitis riparia, vitis ripestris => suffer from chlorosis in chalky soils
=> hybrids have been developped with vitis berlandieri that are more resistant to lime.
=> level of lime must be assessed prior te planting
to what problem leads excess salinity?
will disrupt water uptake and vine nutrition.
to what problem leads excess acidity?
To aluminium toxicity
What rootstocks are generally more tollerant of damp conditions?
vitis riparia based rootstocks
what rootstocks are more drought tolerant?
vitis rupestris
what rootstocks have a low level of vigour?
- riparia rootstock
- => for high-density vineyards
- => for fertile soils in cool climate
what rootstocks have a high level of vigour?
- rupestris rootstock
- => for high-yielding, low density vineyards
- => for poor soils in dry conditions
