D1: Hazards Pests and Diseases

Question 1

Drought:

Answer 1

Vines need water to grow and to produce good quality fruit at yields that make grape growing financially viable

• • Min 500ml in cool climate per year
• • Min 750 mm in warm

Question 2

What can drought do to the vine ?

Answer 2

The vine will close the stomata of the leaves in order to limit water loss

• • this reduces photosynthesis
• – the growth of the plant slow down
• — grape size is reduced and ripening slows down
• —– potentially unripe grapes and lower yields
• ——region that depends on irrigation are at risk for several dry years and scarce watersupply and a entire vineyard can be lost

Question 3

What are the management options for drought?

Answer 3

1) where it is allowed irrigation systems should be considered as part of the initial design of vineyard. If later it will be difficult and disrupting vineyards
2) Droughtresistant rootstocks: V Rupestris and V Berlandieri parentage (eg 110r, 140r)
3) drought tolerant grape varieties: Garnacha

Question 4

What with excess of water ?

Answer 4

1) too much vegative growth in summer
- - this can compete with graperipenng
- - fruit is too much shaded
- – both results in less ripeness

2) can make the canopy prune to fungal diseases because of high humidity

3) if soils are not free draining: the soil becomes waterlogged, reducing the amount of oxygen available in the roots
- - slowing down growth —- kill

4) Compaction of the soil: difficult to work and uncontrolled water run off

Question 5

Which management options would you consider for excess of water ?

Answer 5

If it is in a region with rainfall on a regular basis: the planning of the vineyard must ensure that the issue is adressed by, where possible, planting on a slope or on free draining soils, to improve drainage
— or drainage constructions

Question 6

What with untimely (voortijdig) rainfall ?

Answer 6

1) during pollination and fruit set: can lead to millerandage or coulure
- - reducing the size of the crop and potentially also lowering the quality

2) Rain in mid season: reduce rate of ripening of fruit
- - mild waterstress before véraison reduces shoot growth and allow the grapes to ripen more satisfactorily

3) Heavy rain before vintage: grapes get swollen with water (reducing concentration and quality
– grapes split
— grey rot
—- makes the harvest work difficult
difficulty using meachanical harvesters or accessing the vineyard if on clay soils

Question 7

What are the management options for untimely rainfall ?

Answer 7

Nothing can be done about the incidence or amount of rainfal.

however:
- Site selection, climate in general, slope, condition of the soil and adequacy (voldoendheid) of drainage can mitigate some effects

Monitoring weather forecast: long period of rain:
– option of early harvest with potential of less ripe fruit
or later harvest

Question 8

Freeze:

Answer 8

Fully dormant vines are relatively hard and can tolerate some frost.
howerver under -20°c -4f the vine can be seriously damaged or even killed by winter freeze
— if vines are grafted on a rootstock, the graft is at serious risk, the canes and cordons are second
— frost can kill canes or cordons (reducing yield) or kill all parts of the vine

Question 9

What are the management option in regions with regularly very cold winters?

Answer 9

1) Site selection:
- hill sites can be 5°c 9°F warmer than valley floors
- large or deep bodies of water can give a moderating effect
- vines should be planted where snow settles mot thickly
- – a deep layer of snow protects the vine

2) Choise of varieties:
- winter resistent: cab franc, riesling
- - some american ( eg concord can withstand temp down to nearly -30°c -22°f
- – mongolian species (V Amurensis)
- —- as are hybrids that have these species as parent

3) Protecting vines:
- building up soil around the vine graft (hilling up), the soil underground is a few degrees below freezing
- burying vines, extreme climates, very costly and a lot of labour every year
- vines can also be pruned to have several trunks, so that those killed in winter can be replaced

Question 10

Frost:

Answer 10

These occurs when cold air below 0°c 32°f collects at ground level:

• freezing water in the vines growing buds and shoots
• cold winds blowing across the vineyard after budburst are also very dangerous
• • freeze to newly burst buds or young shoots that have high water content, can be killed

Question 11

Vines in a range of climates are vulnurable (kwetsbaar)

Answer 11

1) Cool climates: the doesnt respond below 10°c/ 50°f
2) Warmer areas: the vines begin to grow and can be damaged when the temp drops

– if buds and young shoots are killed, the growth continues wiith secondary buds, theyre less fruitful and will take longer to ripen

Question 12

There are two types of frost:

Answer 12

1) Advective frost: caused by large volumes of cold air moving in from very cold areas
2) radiative frost: heath being lost on still, cool nights: the earth is heated by the sun and releasing it during the night. tha amount of heat loss depends on cloud cover.
- - windless night will allow a layer of freezing cold air to develop just above the surface of the soil

– cold air is denser than warm air, this freezing cold air will collect in valley bottoms

Question 13

There are several options for the grape grower where frost is an issue. these can be divided into actions that seek to reduce the risk of frost and those that seek to combat hazard if frost does strike:

Answer 13

1) reducing the risk:
- Site selection: avoid frost pockets( places where cold air collect), choose hillsides where cold air can drain away
- Delaying pruning postpones (uitstellen) budburst into warmer months. if buds at the end of canes gets frost, they can be removed.
- choosing variety that buds late (riesling) can help
- vines trained high off the ground (coldest air is near the ground)
- having bare soils (rather than a cover crop) absorb more heath during the day and radiates this heat during the night

2) When frost threatens:
Water sprinklers, wind machines, oil or propane gas burning heaters

Question 14

What about water sprinklers against frost:

Answer 14

also known as aspersion: if the vineyard already has an irrigation system, then the sprinklers can be used to frost protection

• • the water freezes around the parts of the plants, it releases latent heat, protecting the plant.
• • this system must be kept on until the temp rises
• — the cost are for equipment and water. can be much lower thn wind machines or heaters, although not if the cost of water is high

Question 15

Wind machines against frost:

Answer 15

a) 4-7m high, pull warmer air from above down to ground level — raising the temp
b) these are effective where there is an inversion layer: a warm zone of air 10m above the ground (+3-5°c, 5-9°f)

c) the investment is warranted (gewaarborgd), where there is a 20% chance of a damaging radiation frost in any one year
d) the initial investment is considerable

e) helicopters can be used to create the same effect, but theyre expensive

Question 16

oil or propane gas burning heaters against frost:

Answer 16

Also known as Smudge pots and wax candles (bougies

• can be placed in vineyard where the frost is
• high cost of fuel, labour
• • has an low heating efficiency and contribution to air pollution (verontreiniging)

Question 17

Hail, pellets of frozen rain, can cause severe damage to vines at various stages of development:

Answer 17

1) damage and rip (scheur) young shoots and leaves
2) ripening grapes can both be damaged and become a point of entry for botrytis and other diseases.
3) Reducing yields in current and following season
4) if damage is caused early, reshoot from existing buds
- - the occurance of hail is unpredictable in general although in some regions (parts of Argentina, Burgundy) have suffered repeatly

Question 18

What are the managemant optionss against hail ?

Answer 18

1) Rockets may be fired into tunderclouds, seeding them with silver iodide to cause rainfall rather than hail
2) in areas with regular hail: net the fruit zone, netting creates some shading, so only in parts with lot of sunlight (more appropriate in Argentina than Burgundy
3) hail can be very selective, so number of plots in different areas
4) additional cost of crop insurance

Question 19

What about sunburn?

Answer 19

In prolonged hot weather, sunexposed grapes can be sunburnt

• • grape transpiration is limited, so less more effective than leaf transpiration
• — so grapes can reach higher temperatures than the leaves and become burnt
• • vines with already water stress has a higher risk
• • scars in the skin of the grapes
• • death in extreme cases
• • browning the grape, bitter taste
• • increased susceptibility to rot (due skin damage)
• • sunburnt grapes need to be removed

Question 20

What to do about sunburn ?

Answer 20

1) Row orientation and aspect can reduce hot afternoon sun: no east to west orientation on the northern hemisphere, otherwise too much exposure
2) the amount of direct sun exposure can be adjusted through canopy management: partially shade the fruit in hot regions
3) if a heatwave is forecast, additional irrigation, where allowed, may be applied to reduce water stress and sunburn
4) special agricultural sunscreen spray can be applied
5) vines can be shaded with a cloth or net

Question 21

WHat about fire?

Answer 21

a) common in hot and dry countries
b) warmer dryer weather associated with climate change has seen an increase in the incidence of fires
c) outside of human control, so difficult to prevent
d) vineyards near woodland, pastures (weilanden) or other crops may be more at risk as they provide fuel for the fire
e) cover crops and organic mulches can also be fuel
f) cannot be spread on bare, cultivated soils
g) damage may be to property, equipment and irrigation systems or if severe to the vine and their trellising
h) smoke taint

Question 22

What to do about fire ?

Answer 22

• installing fire detectors and sprinklers
• installing and maintaining a water tank
• providing employee training for action in the event of an emegrency

Question 23

What about smoke taint:

Answer 23

a) can give smoky or plastic aromas in the final wine
b) effect on fruit from veraison onwards
c) aroma compounds in smoke can be absorbed by the grapes
- - once in the grapes these compounds often bind with sugar and form aroma-less percursors.
- – similar to other aroma’s these compounds only get aromativ through the fermentation process
- — the strength of the aroma can increase during the ageing of wine

Question 24

what to do about smoke taint ?

Answer 24

a) Affected musts can be tested analytically and/or by micro- vinifications (to release smoke aromas) in the days leading up to harvest, to establish the extent of the problem
b) when the smoke percursors are present on the inside of the grapes
- - hand harvesting, gentle or whole bunch pressing, lower ferm temp and reduced maceration can reduce uptakes of these compounds

– Flash détendte and reverse osmosis can also help but will not remoe the taint completely

Question 25

what are pests ?

Answer 25

a) Pests are organisms that harm the vine and impact the production of grapes in a negative way
b) some compete for water and nutrients, others attack the vine directly
- — affecting yield and quality

c) grape growers have to evaluate the seriousness of the attack and decide wether measures need to be taken
- - evaluate the economic costs of actions taken in relation to the potential damage

Question 26

Some major pests and diseases are the result of insects and fungi being imported from one teritory where the vine species has natural resistance to another.

Answer 26

Phylloxera and the two common forms of mildew were native to north america, but became serious threats when they were introduced into europe

• • the european grape vin V Vinifera has no natural defence against these pests and so succumbed (bezwijken) to them
• —the use of american rootstock with a european Scion (ent) – these can combat the disease

Question 27

Phylloxera:

Answer 27

1) this aphid like (bladluis) insect feeds on and lays eggs on the roots of grape vines.
- it weakens the roots and cause swellings and cracks
- – these than lead to rot over years and the vine can die
2) can be spread by crawling, flying and commonly transported by humans (roots of young vines, equipment, soil)
3) indentified in 1863 in EU, accidentally introduced from the usa and destroyed 2/3 of the EU vineyards in late nineteenth century

Question 28

What are the symptoms of phylloxera ?

Answer 28

1) vines die of drought in patches (scheuren) that increase in size year by year
2) Vine roots are covered with the insects and yellow eggs
3) swellings on older roots
4) pale green leaf galls (zwellingen) on the under surface of the leaves
5) slow stunted shoot growth and leaf yellowing apears after 3 years and the vine actually dies in 5 years

Question 29

What to to about phylloxera ?

Answer 29

1) American rootstocks: V Berlandieri, V Riparia, V Rupestris: these forms hard, corky layers that surround the eggs, sealing the wounds and preventing invasion by bacteria or fungi
- – american vines led to different aromas in the wine, so graft EU varieties on AM rootstocks
2) American rootstocks have problems with typical calcareos soil (low lime intollerance) – chlorosis: leaves yellow, low photos. and reducing yields and quality.
- — solution: hybrids from AM and EU to create protection against phylloxera and better uptake for lime
3) The development of many hybrid rootstocks with complex parentage, can deal with a number of problems: phylloxera, nematodes, extremes of soil ph, water stress, salinity and control the vigour of wine
4) today grapegrowers gets professional advice on the choice of rootstock (vigour, soil, …)
5) expensive, but almost always considered as a standard part of the cost of establishing a vineyard

Question 30

Nematodes:

Answer 30

a) tiny worms, very small, common in soil and too smaal to be seen by the naked eye
b) some cause damage by feeding off vine roots, cause slow, gradual decline (afnemen)
- - others transmit viral diseases: eg Fanleaf virus is spread by the dagger nematode

c) the two most commonly occurring: Root- kno nematode and dagger nematode
d) once present they can only be managed, not eliminated !!!

Question 31

What are the management options for nematodes ?

Answer 31

soil samples are taken to the laboratory to determine number and type of nematodes present various options are available to combat nematodes:

a) leaf the soil fallow for a few years (very expensive, no crop)
b) fumigate the soils (begassing, uitroking) banned in most regions
- – plough in cover crop of mustard plants (works as biofumigants, killing nematodes

c) best solution: nematode-resistant rootstocks

Question 32

a number of diferent grape moths do damage to vines by feeding on flowers and grapes:

Answer 32

Many species have several generations per season:

• attacking flowers in spring
• • grapes later in the year

The wounds are vulnerable to further attack from bacteria and fungi (botrytis)

the most common types:

a) Light brown apple moth in australia
b) The EU grapevine moth in southern EU
c) Grape Berry moth in central and eastern North america

Question 33

what to do about grape moths ?

Answer 33

1) biological controls include the use of:
- bacterium (Bacillus Thuringiensis (which produces substances that are toxic to the moths)
- use of pheromone capsule to disrupt mating (sexual confusion)
- natural predators (parasitic wasps, green lacewings, some spider species)

2) insecticides can be used

Question 34

what about spider mites ?

Answer 34

a) several types of mites can damage th vine, but spider mites are the most detrimental (nadelig)
b) the species from spider mites differ from region to region:
- pacific spider: california
- red spider annd two forms of yellow spider: EU

c) they feed on the surface cells of leaves
- - leads to discoloration
- – less photosynt
- — delayed ripening and reduction in yields
d) they thrive in dusty conditions and are most damaging when vines are already water stressed

Question 35

What to do about spider mites ?

Answer 35

1) make the environment inhospitable by the use of water sprinklers and or cover crops or mulches to reduce dust
2) encourage predatory mites that feed on spider mites
3) general pesticides may kill benefical predatory mites
- - specific sprays can be applied to kill only the mites that are problematic in the vineyard, but this can add costs

Question 36

Other insect pests include leafhoppers( direct damage to vine leaves) and ladybirds (lieveheersbeestjes) which can:

Answer 36

cause taint to the wine if they are in amongst harvested grapes

Question 37

In nature, vines rely on birds to spread their seeds, however:

Answer 37

birds can be a serious threat to grape growers as they destroy an entire crop of grapes as they ripen.
– isolated vineyards that provide the only source of food in the area are at most danger

– in addition to physical damage, it allows also bacteria and fungi to enter bunches which leads to rot

starlings(spreeuwen), attacks

Question 38

What are the management options for birds?

Answer 38

1) the cost of total netting can be justified in regions where birds are a seirous threat
2) Bird scarers or noises, but must be rotated regularly to avoid the birds getting used to them
3) falcons (valken) are sometimes used to deter (afschrikken) unwanted visitors

Question 39

Mammals:

Answer 39

1) they can do damage in vineyards by eating shoots, grapes and leaves, breaking the skin of the grapes and thereby making them vulnerable to rot
- - damaging structures such as trellising
- - they reduce yields, lower the quality and introduce extra cost in repairing the damage

2) a range of animals are pests in different parts in the world: deer, rabbits, kangaroos, raccoons, wild boar and baboons (bavianen)

Question 40

What to do about mammmals ?

Answer 40

Fencing, but sufficiently high and sunk into the soil to stop burrowing animals

Question 41

What about Powdery Mildew:

Answer 41

1) Fungus: Erysiphe Necator, commonly: Oidium tuckeri
- - specific to grape vines

2) American species less vulnurable than V Vinifera
3) introduced in EU in the mid 1800s
- - now the most widespread vine diseases around the world
- - some varieties more susceptible than others (Chardonnay and CS, PN and riesling less)

4) Overwinters in buds and on canes
- - then attack young, green parts of the vine
- - starts with dull grey patches and become black patches as they advance
- – patches can damage young shoots, inflorescences and grapes, reducing yields
- – grapes can also split at véraison and become targets for other diseases

5) the growth rate is determined (nadelig) by temp: Ideal 25°c 77°f
- - shady conditions
- - does not require high humidity
- - can thrive in dry conditions
- — especially in dense shady canopies

Question 42

What are the management options for powdery mildew?

Answer 42

1) Open canopy, reduce shade and density of leaves
2) App of sulfur helps to prevent and threat the disease
- - spray the vines a couple of weeks after budburst and up to véraison
- – spray early in the season as the disease is easier to prevent than to contain if it gets established
3) systematic fungicides can be effective and as they penetrate the green tissue, are not washed off by rain
- - the fungus can become resistant to some fungicides os only limited app in one year

Question 43

Downy mildew:

Answer 43

1) caused by Peronospora: mould (schimmel) that lives within vine tissue, not on surface
- - introduced from north america in the last quarter of 1800s and now common in most wineregions

2) it attacks green parts of the plants, especially young leaves and flowers
3) reducing yields by defoliating (ontbladeren) the vine
- - grapes can also be affected, but is less important than defoliation

4) it needs rainfall and warm temp 20°c 68°f to spread
- - high risk periods are warm springs and stormy but warm summers
5) symptoms: Yellow circular oil spots and then white, downy fungal growth on the underside of leaves

Question 44

What to do about Downy mildew:

Answer 44

1) Sprays from copper salts have been used to prevent the spread
- - bordeaux mixture: Copper and lime (kalk)
- - standart tratment from the 1880s
- - only lasts until 20 mm of rain has fallen
2) other fungicides can also be used and should be applied from about month after budburst to véraison
3) good drainage and an open canopy that dries quickly are helpful to avoid the fungus developing and spreading

Question 45

Grey rot:

Answer 45

1) caused by fungus Botrytis cinerea:
- loss of yield and drops quality
- - affected fruit should be selected out at harves
2) grapes are vulnerable if there are any points of entry (grapes having rubbed against each other in tight bunches or punctured by birds/insects) leading to whole bunches being attacked
3) if the flowers are affected, the funges can stay dormant in the grapes and re emerge after véraison
4) varieties with tight bunches or thin skin are most at risk (semillon SB PN

Question 46

Eutypa Dieback:

Answer 46

1) Dead arm
2) fungal trunk disease
3) leads to rotten wood in vines
4) can affect whole vineyard
5) Reduce yields and kills vines over a ten year period if not tackled
6) Spores are spread by wind over long distances
7) Infection occurs during pruning WOUNDS in moderate temp and especially during rain
8) the effects are evident in spring with short young shoots and yellow leaves
9) Grenache, CS, SB are susceptible among others
10) Prevalent in south AUSTralia, SOuth west france and parts of california

Question 47

What to do about eutypa dieback ?

Answer 47

1) pruning late and applying fungicide to pruning wounds
2) affected trunks can be cut back 5-10cm beyond the visible symptoms and treated with fungicide
- - dead wood must be burnt to avoid spores spreading
3) some biological controls (bacillus subtilis) may be affective
4) if badly affected: retain from a sucker (shoot that grows from the base of the vine) left on the trunk — causes a loss yield for two years
5) removing the vine and replanting it

Question 48

Phomopsis cane and leaf spot:

Answer 48

1) fungal disease that causes a reduction in crops
2) prevalent in years with cool and wet springs
- - followed by humidity and moderate temperatures
3) infected canes whiten and break off easily
4) shoots from these canes develop brown cracks at their bases
- - leaves are also affected
5) grenache is very susceptible
- - cab s is less prone to it

Question 49

Phomopsis management options:

Answer 49

1) fungicides should be applied three weeks after budburst and then again every two weeks if wet conditions continue
2) diseased wood should be removed and burnt
3) its best to prune early or late and not in rainy weather

Question 50

ESCA (black measles, Petri disease, black goo):

Answer 50

1) Complex fungal disease
2) caused by a group of organisms particularly prevalent in warmer and drier climates
- - southern EU and California
3) enters the vine through pruning wounds
4) symptoms: tiger striping leaves and spotting inside the wood
5) reduce the yield of the plant and leads to its death within a few years

Question 51

What to do about ESCA?

Answer 51

1) no chemical controls
– prevention:
° disease free stock
° new, less detrimental pruning techniques
° not pruning in the rain
° removing prunings promptly from the vineyard
° desinfecting pruning wounds
2) research with biological agents such as Bacillus subtilis

Question 52

Other fungal diseases are black rot, black foot disease, bot canker, anthracnose

Answer 52

oke

Question 53

What is the Pierce disease ?

Answer 53

1) Bacterial disease
2) quickly kill vines
3) Amercan continent
4) southern usa and central america
5) the bacterium lives in the sap channels of vines
- - Which it clogs, leading to shrivelling, dropping leaves and the death of the vine between one and five years
6) The bacterium is spread by The SHARPSHOOTER
- - acts like a vector (an organism that transmit a disease)
7) the sharpshooter has led to the disease being spread more rapidly from the 1980s
8) some vines are more susceptible than others: PN chardonnay

Question 54

What to do about Pierces Disease ?

Answer 54

1) no chemical control
- - exact symptoms are unclear
- – vines need to be tested in laboratory for certainty
2) control is by reducing the number of the vector:
- - removing vines close to rivers has been effective
- — riverbanks can be a habitat for one of the vectors (blue green sharpshooter)
3) some chemical insecticides can also be used
4) introducing a species of wasp that feeds on the eggs of sharpshooter
5) strict quarantine rules for the movement of plants to prevent the further spread of the disease
6) work is being done on developing pierces disease resistant vines

Question 55

What are grpe vine yellows?

Answer 55

1) a group of diseases caused by a type of bacteria
2) serious threat to viticulture as there is no treatment available
3) Spread by vectors: leafhoppers include
- - also by nurseries selling untreated, diseased stock
4) common type in europe: Flavescence dorée, which spread rapidly through much of france in the second half of the twentieth century
- - also in germany, southern europe NY State, and in a different form in australia

5) Symptoms: delayed budburst, drooping posture (neerhangende houdeing) because the new shoots fail to become woody, and the canopy turning yellow (in white varieties) and red (in black varieties)
6) in some strains the vine dies as the disease develops, in others it can recover after an attack
7) the bacteria can live in a range of plants: including cover crops used in vineyards
8) Riesling and chardonnay are among the most vulnurable varieties

9) the economic impact is through drastically reduced yields and lower quality (high acidity and low sugar contents of grapes)

Question 56

What to do about grapevine yellows ?

Answer 56

1) no control
2) focus on controlling the vector:
- - leafhopper populations can be reduced by insecticides
- - and the plants that host the hoppers, including cover crops, should be removed
3) best practice in the nursery is to bathe the pruning wood in hot water to kill the disease

Question 57

What is the fanleaf virus ?

Answer 57

1) long standing group of diseases (fanleaf degeneration) that is now found around the world
2) early shoot growth is stunted (belemmerd)
3) canes can grow in disorted ways and leaves are very pale, malformed and can look like a fan

4) can have little effect, to loss of most crop with susceptible varieties as CS

5) The disease was spread enormously by the move to grafted vines, following phylloxera and the inadvertent use of infected plant material
- – also spread slowly by dagger nematodes

Question 58

What to do about fanleaf virus ?

Answer 58

1) no cure, affected vines need to be removed, adding to cost
2) before vineyards are replanted, soil test to check the present of dagger nematodes
- – and only virus tested clean planting material should be used

Question 59

What is the leafroll virus ?

Answer 59

1) Group of viral diseases widely present around the world
2) spread by grafting and mealy bugs
- - key pest in south africa, the mediterranean, argentina and some parts of california
3) does not kill the vines, it can reduce yield by up to half and affect quality negatively
4) slows down the growth of roots and shoots
5) survival fruit may take several additional weeks to ripen and have more acidity, less colour and lower sugar levels
6) the overall health of the vine is also affected as it stores less carbohydrates

7) the typically downward rolling of the leaf usually occurs in autumn
- - the leaves change colour in the autumn to red for black varieties and to yellow for white varieties

8) symptoms not always clearly: so tested in laboratory
9) some vines and carry the virus without showing symptoms

Question 60

What are the management options for leafroll virus ?

Answer 60

1) no cure, remove unproductive vines and replant with virus free stock
2) nurseries can screen vines for virus infections
3) mealy bugs favour humid environments: so open canopies help to reduce pest
4) control by spraying is difficult because of the mealy bug’s waxy coating
5) encourage the mealy bugs natural predators: ladybugs, lacewings and others