Chapter 8: Hazards, Pests & Diseases Flashcards
1.2.3 - Vineyard Management Options: Managing hazards; Managing pests & diseases (131 cards)
1
Q
What are the 9 leading environmental hazards that can affect vineyards and grapes?
A
- Drought
- Excess of water
- Untimely rainfall
- Frosts
- Freeze
- Hail
- Fire
- Smoke taint
- Sunburn
2
Q
Explain how drought impacts the vineyard
A
Lack of water causes a vine to close the stomata on their leaves in order to limit water loss. This, in turn, reduced photosynthesis. If this continues, the growth of the plant is impaired, grape size is reduced, and ripening slows down potentially resulting in unripe grapes and lower yields. If prolonged, the plant will lose its leaves and then die.
Whole vineyards can be lost if water is scarce and no irrigation, e.g., Olifants River in S. Africa
3
Q
Identify the management options for drought
A
- Consider irrigation as part of the initial design of a vineyard (where irrigation is permitted)
- Choose drought-resistant rootstock, e.g., V. rupestris and V. berlandierie (110R and 140R)
- Choose a drought-tolerant variety, e.g. Garnacha
4
Q
Explain how an excess of water can impact the vineyard
A
- Lead to much vegetative growth, which can compete with grape ripening and too much shading of fruit (thereby reduing production of anthocyanins and tannins, and overproduction of methoxypyrazines), resulting in delayed or less ripening in grapes
- Increases humidity, thereby making the canopy more prone to fungal disease
- Waterlogging can occur if soils aren’t free-draining, which reduces the amount of oxygen available to the roots, which slows down growth and eventually kills the vine and can also lead to compacted soils, making them difficult to work, and uncontrolled water run-off
5
Q
Explain how growers manage excess water
A
If in the planning stage:
* plant on slope
* plant on free-draining soil
If planning or on existing vineyard:
* construct drainage system
6
Q
Describe the potential consequences of untimely rainfall at pollination, mid-season, and right before harvest.
A
- Pollination (& fruit set): cmillerandange or coulure, which reduces the size of the crop and potential quality
- Mid-season: slowed ripening of the fruit as mild water stress before véraison reduces the growth of shoot tips, which allows the grapes to ripen more satisfactorily
- Close to Harvest: (1) grapes bloat which reduces the concentration of must and quality of wine and the grapes can split, leading to grey rot; (2) makes working harvest very difficult, e.g., difficult using technical harvesters or pickers accessing the vineyard esp if on clay soils
7
Q
Explain how growers manage untimely rainfall
A
Choice of site (climate in general, slope), condition of soil, choice of whether or not to grass the land between rows of vines and adequacy of drainage mitigate some effects
Monitor weather forecast and weigh options of early harvest with potentially less-ripe fruit or taking a chance on the weather improving in time for a successful later harvest or losing par tor all of the crop
8
Q
Explain how a freeze may impact a vineyard
A
If temps <-20ºC (-4ºF), then serious damage or even death can occur even though fully dormant vines are relatively hardy
Graft is part most at risk if above surface; cans or cordons are next at risk
Frost can kill canes or cordons, which reduces yields, or all parts of the vine above the ground
9
Q
Identify the region most likely affected by freezes
A
Continental climate, e.g Canada, Washington, China
10
Q
Explain how growers manage freeze risk
A
- Site selection: (1) hillside sites can be up to 5ºC (9ºF) warmer than valley floor; (2) large or deep bodies of water benefit from moderating effect; (3) plant vines where snow settles most thickly as deep layer of snow can provide insulation for vines
- Choice of varieties: (1) resilient against winter freeze (Cab Franc, Riesling), or species that are extremely wind hardy (parents are American and/or Mongolian species
- Protect the vine: (1) build up soils around vine graft (hilling up) but doesn’t protect trunk or canes/cordons; (2) bury vines (very expensive as labor intensive - China); (3) prune to have several trunks so if killed in winter can be replaced
11
Q
Describe when frosts occur
A
Cold air below 0ºC (32ºF) collect at ground level,
Cold winds blow across the vineyard after budburst
12
Q
Explain how frost impacts the vineyard
A
If happens to newly burst buds or young shoots that have a high-water content, it freezes the water, thereby killing the buds and/or shoots. The damage and impact on yields can be enormous.
13
Q
Identify which regions are most vulnerable to frost
A
Cool climate - vine responds to regular low temps by not growing until mean air temp of 10ºC (50ºF) is reached
Warmer areas vulnerable because vine begins to grow and will be damaged if drop in temp; however, if buds and young shoots are killed, vine may put out more shoots from secondary buds, but these are less fruitful and take longer to ripen
14
Q
Identify the two types of frost
A
- Advective frost
- Radiative frost (or inversion frost)
15
Q
Explain why ‘advective frost’ occurs
A
Advection frost occurs when very cold, frost-carrying air blows into a vineyard region and displaces warmer air. Unusual in the spring and more associated with winter conditions.
16
Q
Explain why ‘radiative frost’ occurs
A
Radiative frost, also known as inversion frost, is a result of heat being lost on still, cool nights. The earth is heated by the sun during the day and releases that heat during the night. The amount of heat released depends on the level of cloud cover. If the air is not impeded by cloud cover a layer of freezing cold air will develop just above the surface of the soil. This layer of cold air is denser than warm air and, therefore, will be trapped beneath a layer of warmer air and cannot escape. This type of first is most likely to damage vines and is the one that can be more easily, albeit expensively, controlled.
17
Q
What are four ways a grape grower can combat a sudden threat of frost?
A
- Aspersion
- Wind machines
- Smudge pots
- Wax candles (bougies)
18
Q
Explain how owner can reduce the risk of frost in the vineyard
A
- Site selection - avoid frost pockets and choose hillsides where cold air can drain away
- Delay pruning to postpone bud burst
- Choose a late budding variety, e.g., Riesling, Meunier
- Train vines off the ground away from the coolest air which is near the ground
- Bare soil between vines rather than cover cop, which absorbs more heat during the day and radiates the heat during the night
- Leave additional canes on the vines (sacrifice canes) and then remove if there has been no frost damageE
19
Q
Define ‘aspersion’
A
Irrigation sprinklers used or installed specifically for frost protection; as the water freezes around the parts of the plants, it releases latent heat, protecting the plan.
Need to keep going until temp rises and is expensive in terms of equipment and water, but much lower than wind machines or heater so long as cost of water isn’t high
Only method to fight advective frosts
20
Q
Explain how wind machines protect a vineyard from frost
A
Large fans pull warmer air from above down to ground level, thereby raising the temp. Effective when there is an invasion layer, i.e., a warm zone of air 10m above the ground (+3-5ºC (5-9ºF))
21
Q
Identify the pros and cons of wind machines against frost
A
Investment warranted if there is chance of damaging radiative frost once every 5 years or less
Initial investment is considerable
Helicopters can create the same effect; expensive but may be worthwhile if severe, short-term risk
22
Q
Identify the disadvantages of smudge pots and bougies
A
High cost of fuel and labor
Low heating efficiency
Contributes to air population
23
Q
Explain how hail can impact the vineyard
A
- Perforate or knock off young shoots and leaves
- Grape skins can tear, introducing points of entry for botrytis and other diseases
- Yield reduction in that vintage (knocking off clusters) and in next year’s yield
Unpredictable in general, although some regions suffer repeatedly, i.e., Argentina and Burgundy
24
Q
Explain how growers can help management the risk of hail
A
- Fire rockets into thunderclouds, seeding them with silver iodine to cause rainfall rather than hail
- If experience regular hailstorms, e.g., Mendoza, net the fruit zone, but this also creates shading so can only be used in areas with high levels of sunlight
- Have a number of plots in different areas in high-risk areas
- Additional cost of crop insurance against hail
- Rely on vine being able to reshoot from existing buds if damage caused early in the season
25
Explain how sunburn occurs
Sun-exposed grapes can become sunburned in prolonged hot weather because grape transpiration is limited and therefore less effective than leaf transpiration. As a result, grapes can reach higher temps than leaves and become burnt. Grapes on vines that are water stressed are more at risk.
26
Identify the impact of sunburnt grapes on the vineyard
1. Sunburn leads to scars on the skin of grapes and, in extreme cases, to eventual death of the grapes.
2. Negative impact on overall grape quality – browning of the grape, a bitter taste and increased susceptibility to rot (due to skin damage)
3. Yield reduction, as sunburnt grapes must be removed during sorting
27
Identify the options for managing the risk of sunburn in the vineyard
* Proper row orientation and aspect consideration for new vineyards will reduce impact of hottest afternoon sun, i.e., avoiding east-west row orientation otherwise grapes on south side subject to sun all day, especially intense afternoon sun
* Canopy management to limit amount of direct sun exposure; in hot regions, shade the fruit zone
* If heatwave forecasted, additional irrigation, where allowed may reduce water stress and, therefore, sunburn
* Special agriculture sunscreen spray can be applied
* Shading grapes with cloth or net
28
Explain why increase in fires
Warmer, dryer weather associated with climate change = increased in fires, esp Australia, California and Chile
29
Identify methods for managing the risk of fire
* Establish vineyards away from woodland, pastures, or other crops which could provide fuel for the fire
* Limit cover crops and organic mulches which can also provide fuel for the fire
* Install fire detectors and sprinklers
* Install and maintain water tank
* Provide employee training for action in event of emergency
30
Define 'smoke taint'
Smokey or plastic aromas in the final wine that come from exposure to smoke during the growing season.
31
Explain how the risk of smoke taint can be managed
* Affected musts can be tested analytically and/or by micro-vilifications (to release the smoke aromas) in days leading up to harvest to establish the extent of the problem
* Smoke aroma precursors are inside of grapes so hand harvest, gentle or whole bunch pressing, lower fermentation temp and reduced maceration times can reduce uptake of compounds
* Flash detente and reverse osmosis can also help, but will not remove the taint completely
32
Identify the factors that a grower is dependent on in the spectrum of pests and diseases that will need to be dealt with
Geographic location of vineyard
Climate of the vineyard
Weather in the growing season
Variety, clone and rootstock
33
Define 'pest'
Pests are organisms that harm the vine and negatively impact the production of grapes
34
Identify the major pests impacting vineyards today
Phylloxera
Nematodes (microscopic worms)
Grape Moths
Spider Mites
Birds
Mammals
35
Define 'phylloxera'
Phylloxera is an aphid-like insect that feeds and lays eggs on the roots of grapevines
36
Describe the impact phylloxera has on the vineyard
Damages roots, reducing the uptake of nutrients and water
Damaged roots susceptible to bacteria and fungi
Spreads quickly through crawling or humans, e.g., roots of young vines, soil, equipment, and irrigation water
37
Identify the symptoms of a vine with phylloxera
Leads first to a weakening of the vine, reducing growth and yield and then death
Vines die of drought in patches that increase in size year by year
Vine roots are covered with insects surrounded by yellow eggs
Swellings on older roots
Pale green leaf falls on under-surface of leaves
Slow, stunted shoot growth and leaf yellowing appears in around three years, plant dies after about 5
38
Explain how the risk of phylloxera can be managed
* Use American rootstock and graft on vinifera scions (v. berlandieri, v. riparia, and v rupestris)
* Create rootstock hybrids to balance protection to phylloxera and resistance to lime in the soil (these can be bread for resistance to other pests and hazards, such as nematodes and drought)
* Match best rootstock and variety to soil type
* Plant on sandy soil
39
Identify the three American vines species that are best against phylloxera
V. berlandieri, V. riparia, V rupestris offer the most protection because they have hard, corky layers that surround the eggs, sealing the wounds and preventing invasion by bacteria or fungi
40
Explain why an American hybrid was needed to address phylloxera
A single American variety caused problems in calcareous soils of Europe because they could not tolerate the lime in the soil.
Vines suffered from chlorosis, which turned the leaves yellow, halted photosynthesis, and reduced yields and quality.
An American hybrid balance level of protection to phylloxera and resistance to lime in the soil.
41
Identify other ways a rootstock can influence the vineyard (WORK ON)
Resistance to phylloxera
Resistance of nematodes
Resistance to drought
Resistance to waterlogging
Vigor
. . .
42
Define 'nematode'
Microscopic worms that live in the soil (even if can't be seen with the naked eye) and feed off of vines' roots, reduing yield and vigor.
Nematodes can also transmit viral diseases, e.g., fanleaf virus.
43
Identify the damage caused by nematodes
Some cause damage by feeding off vine roots, significantly reducing yields and vigor - causing a slow, gradual decline
Others transmit viral diseases
44
Identify the two most common nematodes in the vineyard
Root-know nematode causes knot-like growths on the vine and is one of the most widespread.
Dagger nematode spreads the fan leaf virus.
45
Explain how nematodes spread in the vineyard
* Already present in soil
* Spread by unclean nursery stock
* Spread by irrigation water
* Spread by vehicles
46
Identify the options for managing the risk of nematodes in the vineyard
Can't be eliminated, only managed
* Take soil samples and analyze in a lab to determine number and type of nematodes
* Fumigate soil (either by using chemicals (uncommon) or plough in a cover crop of mustard plant, which contains compounds that work as biofumigrants, killing nematodes (common)
* Nematode-resistant rootstocks are best solution, such as Ramsey and Dog Ridge (both V. champini)
* [Buy heat-treated rootstocks (steamed at 44ºC for 120 minutes]
47
Identify two nematode-resistant rootstocks
Ramsey and Dog Ridge (v. champion)
48
Define 'grape moth'
Species of moths that do damage to vines
49
How do grape moths damage vines?
They feed on flowers and grapes, creating wounds in the grapes thereby inviting disease and botrytis.
Because many moth species have several generations per season, on egeneration can attack flowers in spring and the next generation can attack grapes later in the year.
50
Identify the three most common grape moths
Light brown apple moth - Australia
European grapevine moth - S. Europe (imported into Napa in 2009 but declared eradicated in 2016)
Grape berry moth - central and eastern N America
51
Identify the methods for managing the risk of grape moths in the vineyard
Insecticides
Biological controls
* bacterium bacillus thuringiensis (produces substances toxic to moths)
* pheromone capsures to disrupt mating (sexual confusion)
* natural predators (parasitic wasps, green lacewings, some spider species)
52
Explain how spider mites cause damage in the vineyard
Spider mites feed on the surface cells of leaves, causing:
* ldiscoloration of the leaves
* reduction in photosynthesis
* delayed ripening
* reduction in yields.
53
Identify the types of spider mites seen in different regions
Pacific spider mite - most destructive in California
Red spider mite and two forms of yellow spider mites - Europe
54
Explain how the risk of spider mites is managed in the vineyard
* Make environment inhospitable by use of water sprinklers and/or cover crops or mulches to reduce dust
* Encourage predatory mites (by planting host species)
* General pesticides may kill beneficial predatory mites, but specific sprays can be applied to kill only problematic mites - very costly
55
Explain how birds negatively impact a vineyard
Birds can damage grapes or destroy an entire crop as the grapes ripen, which leads to bacteria and disease entering the grapes, leading to rot.
## Footnote
Isolated vineyards that provide the only source of food in an area particularly in danger
56
Identify one species of birds that is an issue in the vineyard
Starlings
57
Explain how the risk of birds can be managed in the vineyard
* Netting over vineyards - cost is justified in high value areas (Mornington Peninsula) or where birds a major threat
* Bird scarers or noises but need to be rotated regularly to avoid the birds acclimatizing to them
* Falcons sometimes used
58
Explain how mammals can damaged a vineyard
Eat shoots, grapes and leaves
Breaks grape skins open, making them vulnerable to rot
Damage structures such as trellising
59
Identify the types of mammals that cause damage in the vineyard
Deer, rabbits, kangaroos, raccoons, wild boar, baboons
60
What is the best way to keep mammals out of vineyards and destroying crops?
Fencing - high enough so can't be jumped over or sunk low enough into soil to stop burrowing
61
Identify 10 fungal diseases that impact the vineyard
Powdery mildew
Downy mildew
Grey rot
Eutypa Dieback
Phomopsis Cane and Leaf Spot
Esca
Black rot
Black-foot disease
Bot canker
Anthracnose
62
Identify the fungus that causes Powdery Mildew and its starting spot
* Erysiphe nectar, commonly called Odium tuckeri
* Introduced from N America to Europe mid 1800s
* Specific to grapevines
63
Identify the grape varieties that are more susceptible to Powdery Mildew
Chardonnay
Cabernet Sauvignon
64
Identify the grape varieties that are less susceptible to Powdery Mildew
Pinot Noir
Riesling
65
Explain how Powdery Mildew can become a problem in the vineyard
* Overwinters in buds and on canes.
* Attacks young, green parts of the vine which shows as dull grey patches, turning into black patches as they advance.
* Black patches damage young shoots, inflorescences and grapes, reducing yield.
* Grapes can be split at véraison and become targets for other infections.
66
Identify the conditions needed for Powdery Mildew to exist in the vineyard
Growth rate determined by temp with optimum temp around 25ºC (77ºF)
Thrives in shady conditions
Does not require high humidity - can spread in relatively dry conditions, especially in dense, shady canopies
67
Explain how the risk of Powdery Mildew in managed in the vineyard
1. Keep an open canopy to reduce shade and density of leaves (preferred approach)
2. Apply sulfur to prevent and treat; spray from a couple of weeks after bud burst and up to véraison; spray early to keep from getting established, i.e. prevent
3. Systemic fungicides can be effective and, because they penetrate the green tissue and not washed off by rain; however, fungus can become resistant so only a limited number can be made in a year
68
Identify the fungus that causes Downy Mildew and its starting location
Peronospora, a water mold that lives within vine tissue, not on the surface
Introduced from N. America in last quarter of 1800s and common in most wine regions
69
Explain how Downy Mildew impacts the vineyard
Overwinters on fallen leaves
Attacks green parts of the plant, especially young leaves and flowers, thereby reducing yields by defoliating vines.
Will see yellow, circular 'oil spots' and then white, downy fungal growth on the underside of leaves
Attacks grapes as well, but not as much of an issue
70
Identify the conditions Downy Mildew needs to exist in the vineyard
Needs rainfall and warm temps (20ºC (68ºF)) to spread
High risk in warm springs and stormy but warm summers
71
Identify the methods for managing the risk of Downy Mildew
1. Sprays made from copper sulfate to prevent spread, e.g., Bordeaux mixture (Combo of copper sulfate and lime) became standard in 1880s - lasts only until 20 mm rain has fallen. Only option for organic growers, although now concern about buildup of copper in the soil and water, and EU looking to reduce and/or ban
2. Other fungicides – best applied about a month after budburst véraison
3. Good drainage and open canopy that dries quickly to help avoid it developing and spreading
72
Identify the fungus that causes Grey Rot and the starting point
Botrytis cinerea causes Grey Rot
73
Explain how Grey Rot impacts the vineyard
Grapes are vulnerable if there are any points of entry (i.e., rubbed against each other in tight bunches or punctured by birds or insects), leading to whole bunches being attacked
If flowers are affected, fungus stays dormant in grape and re-emerges after veraison
74
Explain how Grey Rot spreads in the vineyard
Spores are typically present in the vineyard and become active in periods of rainfall and high humidity
Very common fungus that occurs widely in nature. Likes wet and damp conditions and thrives where sugar is present.
75
Identify the grape varieties most at risk for grey rot
Those with tight bunches or thin skins
Semillon
Sauvignong Blanc
Pinot Noir
76
Identify methods for managing the risk of Grey Rot in the vineyard
Select grape varieties with small grapes and thick skins so high levels of resistance and protect grapes against other pests
Maintain an open canopy and remove leaves around bunches
Sulfur and copper sprays are ineffective, but other fungicides can work. Apply at key points in season - flowering nearly complete, end of grape formation, bunch closure (i.e., when grapes are large enough so that they touch each other) and version; however, becomes resistant if used regularly
Antagonistic bacteria, e.g., bacillus subtitles and other forms of biological control
77
Define 'Eutypa Dieback'
Trunk disease also called Dead Arm that leads to rotten wood in vines and can affect whole vineyards
78
In what part of the vine does Eutypa dieback live?
What does it do to the vine?
Lives in the trunk of the vine
Leads to rotten wood in vines, reducing yields significantly and kills vines over a ten-year period if not remedied
79
Identify the varieties susceptible to Eutypa Dieback
Grenache
Cab Sauv
Sauv Blanc
80
Identify the regions where Eutypa Dieback is particularly prevalent
Australia
SW France
parts of California
81
Explain how the risk of Eutypa Dieback is managed in the vineyard
* Pruning late and applying fungicide to pruning wounds
* Cut back affected trunks 5-10 cm beyond visible symptoms and treat with fungicide, affected wood burnt to avoid spores spreading
* Some biological controls (bacillus subtitles)
* Retrain from a sucker (shoot that grows from base of the vine) left on trunk (which causes a loss of yields for two years) or removing vine and replanting it
## Footnote
Difficult to control
82
The Phomopsis fungus causes a reduction in:
* Crop size
* Leaf size
* Root depth
Crop size
83
Identify which varieties are more susceptible to Phomopsis Cane and Leaf Spot
Grenache
84
Identify which variety is less susceptible to Phomopsis Cane and Leaf Spot
Cab Sauv
85
Explain how the risk of Phomopsis Cane and Leaf Spot is managed in the vineyard
1. Fungicides applied 3 weeks after bud burst and then every two weeks if wet conditions continue
2. Diseased and dead wood removed during pruning and burnt or buried
3. Canopy mgmt techniques to improve air flow within the canopy
86
Identify Esca
Complex fungal disease caused by a group of organisms in warmer and drier climates, e.g., S Europe and California
87
Explain how Esca impacts the vineyard
Esca enters through pruning wounds
Symptoms include tiger-striping of leaves and spotting inside the wood
Reduces the yield of the vine and leads to its death within a few years
88
Explain how the risk of Esca is managed in the vineyard
* Best management is prevention as no chemical controls exist
* Sources disease-free stock
* Use new, less detrimental pruning techniques
* Don't prune in the rain
* Removing pruning promptly from the vineyard
* Disinfect pruning wounds
* Continued research into bacillus subtillis
89
Explain how Back Rot impacts the vineyard
Black rot is impossible to eradicate once present in the vineyard. Controlled by the same spectrum of chemicals used to control other major fungal diseases, e.g., Downy Mildew
90
Identify two bacterial diseases in the vineyard
Pierce's Disease
Grapevine Yellows (group of diseases)
91
Identify where Pierce's Disease originated
Originated on American continent, initially affects southern USA and Central America and is present in California
92
Explain how Pierce's Disease impacts the vineyard
Bacterium lives in sap channels of vines, which it clogs, leading to grape shriveling, dropping leaves, and death of vine between one and five years
93
Identify the symptoms of Pierce's Disease
Exact symptoms unclear so must be tested in lab to determine whether infected
94
Explain how Pierce's Disease is spread in the vineyard
Sharpshooter insect, which as a vector lead to the rapid spread from 1980s on
95
Define 'vector'
An organism that transmits a disease
96
Identify grape varieties more susceptible to Pierce's Disease
Chardonnay
Pinot Noir
97
Explain how the risk of Pierce's Disease can be managed in the vineyard
No chemical control available for bacterium
Control by reducing vectors
- remove vines close to rivers as riverbank habitats for blue-green sharpshooter
- chemical insecticides
- introduce species of wasp that feeds on eggs of sharpshooters
Strict quarantine rules for movement of plants to prevent further spread
Work being done on developing Pierce's Disease resistant vines
98
Explain how Grapevine Yellows are spread in the vineyard
Vectors, including leafhoppers
Nurseries selling untreated, diseased stock
Bacterium also lives on cover crops
99
Identify the most common type of Grapevine Yellow and where it exists
Europe - flavescence doree - spread rapidly through France in second half of 20th century and present in Germany, S. Europe, NY State and, in a different form, Australia
100
Identify the symptoms of Grapevine Yellow
Delayed bud burst
Drooping posture because new shoots fail to become woody
Canopy turning yellow (in white varieties) and red (in black varieties)
Some strains, vine dies, in others, vine recovers
101
Identify the grape varieties most susceptible to Grapevine Yellows
Chardonnay
Riesling
102
Explain how Grapevine Yellows impact the vineyard
Drastically reduced yields and lower quality fruit (high acid and low sugar)
103
Explain how the risk of Grapevine Yellows can be managed
No treatment available
Focus on controlling the vector
- reduce leafhopper populations with insecticides
- plants that host leaf hoppers, including cover crops, removed
Nursery - bathe pruning wood in hot water to kill
104
Identify two bacterial diseases (other than Pierce's Disease and Grapevine Yellows) that impact the vineyard
Bacterial blight
Crown gall
105
Identify two viruses that impact the vineyard
Fanleaf Virus
Leafroll Virus
106
Define 'Fanleaf Virus'
Longstanding group of diseases (also called Fanleaf degeneration) found around the world
107
Explain how Fanleaf Virus impacts the vineyard
Early shoot growth is stunted
Canes can grow in distorted ways
Leaves are very pale, malformed - can look like a fan
Effects vary widely from very little to losing most of the crop
108
Identify the variety susceptible to Fanleaf Virus
Cab Sauv
109
Explain how Fanleaf Virus is spread
Move to grafted vines following phylloxera and inadvertent use of infected plant material
Dagger nematode
110
Explain how the risk of Fanleaf Virus can be managed in the vineyard
There is no cure and eventually the affected vines will need to be replaced.
Before planting - test soil to check for presence of dagger nematodes and use only virus-tested, clean planting material and nematode-resistant rootstock
As with most viruses, only cure is one of removal and destruction of infected material, fallowing the site for as long as possible and replanting with virus-free plants.
111
Explain how Leafroll Virus is spread in the vineyard
Spread by grafting on infected plant material and mealy bug
112
Identify where the mealy bug is a key pest
S Africa
mediterranean
Argentina
some parts of California
113
Explain how Leafroll Virus impacts the vineyard
Doesn't kill the vine but reduces yields by up to half and negatively affects quality
Slows down the growth of roots and shoots
Surviving fruit may take several additional weeks to ripen and have more acidity, less color and lower sugar levels
Overall health of vine affected as it stores less carbs
114
Identify the symptoms of Leafroll Virus
Typical downward rolling of leaves usually occurs in autumn
Leaves change color in autumn to red for black grapes and yellow for white grapes
Symptoms not always clear, so need lab testing
Some vines and rootstocks carry the virus without any symptoms
115
Why is having bare, moist soil in the vineyard desirable (i.e., no weeds, cover corps, or mulches)?
Soil absorbs heat during the day and releases that heat at night, reducing frost risk.
116
When are grapes most susceptible to smoke taint?
From véraison onwards
117
Aroma compounds from smoke taint only become aromatic through the __ process, and become more prounced during the __ process.
**Fermentation** (Aromas compounds in smoke can be absorbed by grapes and then bind with sugars and form aroma-less precursors, which only become aromatic through the fermentation process.)
**Bottle aging** (Strength of aromas can increase during aging of wine and during bottle aging as further aroma precursor break down and become aromatic)
118
How does phylloxera spread?
* These aphids can fly and crawl through soil
* Commonly transported by humans on young vines
* Can be transported on vineyard equipment
* By irrigation water
119
What are the symptoms of a phylloxera infestation?
1. Patches of vines die drought increasingly in size year over year
2. Vine roots are covered with insects surrounded by yellow eggs
3. Swellings on older roots
4. Pale green leaf galls on the underside of leaves
5. Slow, stunted shoot growth and leaf yellowing appears in roughly three years, then plant dies after around five years
120
In what year was phylloxera first identified in Europe?
1863
121
What soils are immune to phylloxera?
Sandy soils
122
What type of mite is most detrimental to grape vines?
Spider Mite
123
What is the spider mite's favorite environment?
* Hot and humid
* Cool and windy
* Dry and dustry
Dry and dusty
## Footnote
They also thrive when the vine is water stressed.
124
Leafhoppers and ladybirds are:
* Insect pests found in vineyards
* Preparations used in biodynamic viticulture
* Common names for oidium and peronospera
Insect pests founds in vineyards
125
Powderly Mildew thrives in which of the following conditions:
* Hot and humid
* Temperate and shady
* Cool and rainy
Temperate and shady
126
How do vines become infected with Eutypa dieback?
Under what weather conditions do the spores spread best?
* Through pruning wounds in the vine
* Spores spread in rainy conditions and moderation temperatures
127
In what conditions does Phomopsis thrive?
Prevalent in years with cool and wet springs followed by humidity and moderate temperatures
128
What happens to a vine that's infected with Phomopsis?
* Infected canes whiten and break off easily
* shoots growing from these infected canes develop brown cracks at their bases
* leaves also infected
129
Black rot, black-foot disease, Bot canker, and anthracnose are:
* Bacterial diseases
* Fungal diseases
* Viral diseases
Fungal diseases
130
Since some vines and rootstocks carry the leafroll virus without showing symptoms, what must a grape grower do prior to planting new vines?
Get them tested for the virus in a lab
131
How do grape growers manage leafroll virus?
* No cure – only solution is to remove unproductive vines and replant with virus-free stock
* Keep an open canopy to reduce humidity, which reduces mealy bug population
* Introduce predators of mealy bugs,e.g., ladybugs and lacewings
* Nurseries can screen vines for virus infections
