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My WSET Diploma D1 > 8. Hazards, Pests & Diseases > Flashcards

8. Hazards, Pests & Diseases Flashcards

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1
Q

What is Pierce’s Disease and how is it spread?

How does it affect vines?

2 examples of varietals that are more vulnerable:

A
  • bacterial disease that quickly kills vines
  • lives in sap channels of vines, clogging them, leading to shrivelling/dropping leaves and death between 1-5 years
  • spread by leafhoppers (specifically Glassy-Winged Sharpshooters)

Chardonnay / Pinot Noir = more vulnerable

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2
Q

What are symptoms of phylloxera? (5)

A
  • vines die of drought in patches that increase each year
  • vine roots are covered with insects and yellow eggs
  • swellings in older roots
  • pale green leaf galls on under-surface of leaves
  • stunted shoot growth/leaf yellowing around 3 years – dies after 5
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3
Q

How does smoke taint “infect” grapes and resultant wines (3)?

A
  • Aroma compounds are absorbed by the grapes, binding w/sugars and forming aroma pre-cursors (not becoming aromatic until fermentation).
  • Wines w/smoke taint will exhibit smoky or plastic aromas.
  • Strength of aromas can increase during élevage and bottle aging as more precursors break down and become aromatic.
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4
Q

What are management options for BIRDS (3)?

A

1) Netting.
2) Bird scarers/noise makers (must be rotated to precent birds becoming inured to them)
3) Introducing predators e.g. Falcons.

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5
Q

3 varietals that are particularly susceptible to Eutypa Dieback?

Which regions has it become particularly prevalent in (3)?

A

Grenache / Cabernet Sauvignon / Sauvignon Blanc

S. Australia / SW. France / California

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6
Q

What are management options for frost? (5)

A

1) Avoid frost pockets/choose hillside sites where cold air can drain away
2) Delaying pruning postpones bud burst into warmer months
3) Choose a variety that buds late e.g. Riesling/Cabernet Sauvignon
4) Vines high-trained off ground (coldest air = near ground)
5) Having bare soil between vines (absorbs more heat during day)

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7
Q

2 examples each of varieties MORE / LESS prone to Powdery Mildew:

A

MORE PRONE: Chardonnay / Cabernet Franc

LESS PRONE: Pinot Noir / Riesling

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8
Q

What are management options for drought? (3)

A

1) irrigation systems (where legally allowed)
2) drought-resistant rootstocks
3) drought-tolerant varieties e.g. Garnacha

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9
Q

How can SITE SELECTION aid in management of winter freezes(3)?

A

1) Hillside sites can be warmer than valley floor.
2) Sites near deep bodies of water benefit from moderating (e.g. Finger Lakes)
3) Planting where snow falls thickest (deep layer of snow protects vine)

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10
Q

What causes sunburn of grapes (3)?

How does sunburn negatively effect the grapes (3)?

A

Excess exposure to sun and heat.

Transpiration rate for grapes is more limited and less effective than for leaves.

As a result, grapes can reach higher temperatures than leaves and become burnt.

  • Prolonged periods of sunburn have a negative affect on grape yields and quality.
  • Leaves scars on the skins and can cause death of grapes as well.
  • Causes browning of skins = bitter tastes + increased susceptiblity to rot.
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11
Q

How do MAMMALS damage vineyards (3)?

What are 4 specific examples?

What is the main management option for them?

A
  • Eating shoots, grapes + leaves.
  • Breaking skins = vulnerable to rot.
  • Damaging structures such as trellising.

Baboons (S. Africa) / Kangaroos (Australia) / Wild Boar (Tuscany) / Deer (N. America)

Fencing is main option (must be sufficiently high + sunk in the soil)

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12
Q

How can PROTECTING VINES aid in management of winter freezes (3)?

A

1) Building up soil around vine graft (“hilling up”)
2) Burying vines (extreme climates)
3) Cultivation of multiple trunks per vine, so those killed in winter can be replaced.

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13
Q

Example of a region which experiences regular hail storms:

A

Mendoza, Argentina

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14
Q

What are some factors that increase the risk of a vineyard’s damage from FIRE (4)?

A
  • Countries/regions that are hotter and drier.
  • Warmer/drier conditions due to climate change.
  • Vineyard locations near woodland, pastures and other crops that provide fuel.
  • Presence of cover crops and organic mulches which provide fuel for the fire.
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15
Q

What is phylloxera and what does it do?

How can it be spread / transported?

A
  • an aphid-like insect that feeds on and lays eggs on roots of grape vines
  • weakens vine roots causing swelling and cracks, leading to rot.

Phylloxera was originally brought from N. America to Europe, and can spread via crawling, flying, or transported by humans on vine roots, soil, irrigation water or vineyard equipment e.g. leaf trimmers and harvesters.

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16
Q

What are nematodes and what do they do (2)?

What are the two most common?

A
  • tiny worms that are common in soil that cause damage by feeding off vine roots and transmitting diseases (e.g. fanleaf virus)
  • reductions in yield and vigor.
  • this decreases ability of plant to uptake water and nutrients
  • two most common are root-knot and dagger
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17
Q

What are management options for untimely rainfall? (2)

A
  • Monitoring forecasts and considering early harvest if necessary
  • Choice of site can also put a grape-grower in a better position from the start (climate, slope, soils, adequacy of drainage.)
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18
Q

What is the difference between a FROST and a FREEZE?

A

FROST: Cold air below 0C / 32F that collects at ground level and freezes water in vine’s buds/shoots.

FREEZE: Temperatures drop below -20C / -4F and vine become seriously damaged.

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19
Q

What are management options for hail? (4)

A

1) rockets can be fired into thunderclouds, seeding them with silver iodide causing rainfall instead of hail
2) net the fruit zone (only suitable in areas w/high sunlight levels, e.g. Argentina vs Burgundy)
3) select a number of plots in different areas
4) crop insurance against hail

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20
Q

What are the symptoms of fanleaf virus (3)?

What are its effects on the crop (2)?

e.g. of a susceptible variety?

A
  • early shoot growth is stunted / canes grow in distorted ways / leaves are very pale + look like a fan
  • Results can vary from little effect to losing most of crop esp. in susceptible varieties e.g. Cab. Sauv.
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21
Q

What is Esca?

How does it affect the vine?

What are its symptoms (2)?

A
  • a complex fungal disease caused by group of organisms that are prevalent in warmer/drier climates e.g. S. Europe and California.
  • enters vine through pruning wounds = reduced yield / death of plant.
  • symptoms include tiger-striping of leaves and spotting inside wood
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22
Q

Explain how Heaters aka “Smudge Pots” protect vines fom frosts:

What are the cons(3)?

A

Oil/Propane Gas heaters are placed in vineyards and lit when there is a risk of frost.

CONS: -High cost of fuel/labor

  • Low heating efficiency
  • Contribution to air pollution
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23
Q

Are vines planted in cool or warm climate areas more at risk from being damaged by frosts?

Why/why not?

How do vines react when damaged by frosts (2)?

A
  • Cool climate areas are vulnerable, but vines respond by not initiating budburst until temps reach 10C / 50F.
  • Warm climates also at risk because if a milder day prompts budburst, then is followed by v. cool weather, buds will be damaged.

If buds / shoots are are killed, vine produces more shoots from secondary buds.

However, these shoots are less fruitful and will take longer to ripen, risking a drop in quality / lack of ripeness.

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24
Q

How can birds be a serious threat to vine growers (2)?

What is an example of a species that often attacks vineyards?

A
  • Birds can destroy an entire crop of grapes by eating them (esp. in areas where grapes are the only source of food.)
  • Damage can also allow bacteria/fungi to enter bunches.

Starlings

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25
Q

What are management options for nematodes? (4)

Once they are present they can only be:

A

1) leave soil to fallow for a number of years (but no crop = loss of $)
2) fumigate soil using chemicals (that are now banned in most regions)
3) plough in a cover crop of mustard plant (contains compounds that kill nematodes)
4) use nematode-resistant rootstocks (Ramsey, Dog Ridge, both V. Champini)

Once present they can only be MANAGED, not ELIMINATED

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26
Q

What are management options for grapevine yellows? (3)

A

There is no control for Grapevine Yellows. BUT:

1) focus on controlling the vectors, i.e. leafhoppers + plants that host them (insecticides / plant removal)
2) best practice in nursery is to bathe pruning wood in hot water

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27
Q

How can CHOICE OF VARIETAL aid in management of winter freezes (2)?

A

1) Some varieties = more freeze resistant (e.g. Cab Franc / Riesling)
2) Some American (Concord) and Mongolian (V. amurensis) vines species are more winter hardy

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28
Q

What causes Powdery Mildew?

AKA?

How does it affect vines (3)?

What conditions does it thrive in?

A
  • CAUSED BY A FUNGUS (Erysiphe necator)
  • AKA “Oidium tuckeri”
  • it overwinters in buds/on canes then attacks young, green parts of the vine (grey patches to black patches).
  • the patches damage the shoots, inflorescences and grapes, reducing yield.
  • can cause grapes to split at véraison = encourages other infections.
  • thrives in shady conditions, temps of ~25C (77F), and does not require high humidity
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29
Q

What are management options for leafroll virus (4)?

A
  • there is no cure = only solution is to remove affected vines + replant.
  • nurseries can screen for virus infections
  • Open canopies help to reduce presence of mealy bugs
  • Introduce predator to mealy bugs e.g. ladybugs, lacewings.
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30
Q

Explain how Wind Machines protect vines fom frosts:

What are the cons(2)?

A

Large fans (4-7m high) pull warm air from above ground to ground level = raised temperature. Helicopters can be used to the same effect.

CONS: -Only effective if there is an “inversion layer” (zone of warm air above ground.)

  • Initial investment is considerable, and may not be economically warranted.
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31
Q

What are the effects of untimely rainfall during:

POLLINATION / FRUIT SET

MID-SEASON

CLOSE TO/DURING HARVEST (2)

A
  • POLLINATION / FRUIT SET = millerandage or coulure = reduced yield+quality
  • MID-SEASON = reduce the rate of ripening fruit (you want water deficiency at this time)
  • CLOSE TO / DURING HARVEST = grapes swell with water = splitting + grey rot, reduced concentration of must/quality of wine.

Also makes harvesting more difficult (e.g. difficulty of mechanical harvesters in clay soils)

32
Q

What is the name of the vine section that is grafted ONTO the rootstock?

A

The “scion”

33
Q

What are management options for Pierce’s Disease? (5)

Why can management be particularly challenging?

A

1) Plant vines away from habitat of insects that spread e.g. riverbanks.
2) Introducing predator e.g. wasps to attack eggs of sharpshooters.
3) Spray w/pesticides to protect against vectors.
4) Remove crops that could harbor vectors.
5) Stricter quarantine rules for movement of plants

There is no chemical control for the bacterium = vines must be tested in lab.

34
Q

How do LEAFHOPPERS cause damage?

How do LADYBIRDS cause damage?

A

LEAFHOPPERS: direct damage to vine leaves.

LADYBIRDS: can taint wines if amongst harvested grapes.

35
Q

Which parts of the vine are most vulnerable to winter FREEZE?

A

The vine graft is most at risk of being damaged, followed by the canes and cordons, which can greatly reduce yields.

36
Q

What are management options for powdery mildew? (3)

A

1) keep an open canopy reduce shade/density of leaves (preferred approach)
2) applications of sulphur sprays (spray ealier for better containment)
3) systematic fungicides ( fungus can become resistant, so must be limited)

37
Q

What is Grey Rot aka?

How does grey rot affect grapes?

When does it become active (2)?

What are the negative results?

Which varietals are most at risk?

A

Botrytis cinera (the harmful form of benign Noble Rot)

  • it affects any grapes with a point of entry (skin puncture)
  • spores are present in vineyard and become active in periods of rainfall and high humidity.
  • If flowers are affected, the fungus can lay dormant in grape and re-emerge after véraison.
  • Results in loss of yield, loss of quality (color, body, aroma/flavor)
  • mostly affects varieties with thin skins and tight bunches e.g. Semillon, Sauvignon Blanc, Pinot Noir.
38
Q

How are nematodes spread (3)?

A

Although already present in many soils, they can be spread by unclean plants / irrigation water / vehicles (e.g. harvesters).

39
Q

What are grape moths and what do they do?

How does this affect the crop?

A
  • moths that feed on flowers and grapes
  • they create wounds that are susceptible to bacteria and fungi = significant crop losses.
40
Q

What are management options for grape moths? (4)

A
  • insecticides
  • bacteria that are toxic to moths (Bacillus thuringiensis)
  • pheromone capsules that cause sexual confusion = disrupted mating
  • introducing natural predators such as wasps / spiders
41
Q

Even though many European PDOs prohibit irrigation, what are 2 circumstances in which it would be allowed?

A
  1. Establishing young vines.
  2. Emergency situations where drought conditions threaten the livelihood of grape growers.
42
Q

What are management options for downy mildew? (3)

A

1) BCD (Bordeaux - Copper - Downy): Sprays made from copper sulfate and lime, “Bordeaux mixture”; lasts until 20mm of rain have fallen.
2) other fungicides (applied from a month after budburst till véraison).
3) good drainage and open canopy that dries quickly

43
Q

What is the minimum amount of water needed by a vineyard per year in COOL and WARM climates?

A

COOL climates: min. 500mm/year

WARM climates: min 750mm/year

44
Q

What are “Grapevine Yellows”?

What are the symptoms of grapevine yellows (3)?

A

A group of bacteria-caused diseases that negatively affect grapevines.

  • delayed bud burst
  • drooping posture (new shoots fail to turn woody)
  • canopy turning yellow (in white varietals) and red (in black varietals)
45
Q

Identify 6 Fungal diseases that can affect grapevines:

A

1) Eutypa Dieback
2) Esca
3) Downy Mildew
4) Powdery Mildew
5) Phomopsis
6) Grey Rot

46
Q

What are management options for spider mites (3)?

A

1) make environment inhospitable by using sprinklers/cover crops to reduce dust
2) encourage predatory mites
3) general pesticides

47
Q

Why is management of Esca difficult?

What must a grapegrower do instead (4)?

A

No chemical controls to cure, so prevention is key:

Disease-free rootstock / less detrimental pruning techniques / not pruning in rain / disinfecting pruning wounds.

48
Q

What happens to the vine during drought?

What will the result of prolonged drought be on vines?

A

Loss of water = stomata closes = reduces photosynthesis.

Reduced photosynthesis = slowed growth, reduced grape size/yield/ripeness.

Prolonged drought = Vines lose leaves + die.

49
Q

What are the 3 categories of management options for winter freeze?

A

1) Site selection
2) Choice of variety
3) Protecting vines

50
Q

What happens during periods of excess water (3)?

A

Leads to too much vegetative growth =

competes with grape ripening/too much shading =

fungal diseases + less ripening.

51
Q

Explain how radiative frosts develop (4):

What areas are more at risk?

A
  • Radiative frosts are the result of a loss of heat on still, cool nights.
  • Earth heats up during the day and releases the heat at night.
  • Amount of heat lost depends on cloud cover (more clouds = less heat loss).
  • Less wind = layer of freezing cold air will develop just above soil’s surface.
  • Cold air is denser, flows and collects downhill, which is why valley floors are more prone to frosts.
52
Q

What are the two types of frosts?

A

1) Advective - caused by large volumes of cold air moving in from very cold areas
2) Radiative - result of heat being lost on cool, still nights

53
Q

What will cause waterlogging to occur (2)?
What effect will this have on the vine?

What effect will this have on the soils?

A

Excess water + non-free draining soils (e.g. high clay content)

VINE: Amount of O2 available to roots is reduced = slowed growth = eventual death of vine.

SOILS: Soils become compacted = difficult to work + uncontrolled water run-off.

54
Q

How is grapevine yellows spread (2)?

What is the most common type Grapevine Yellows (1) and where is it present (5)?

What are the 2 most vulnerable varieties?

A
  • vectors including leafhoppers + nurseries selling infected stock
  • flavescence dorée
  • France / Germany / S. Europe / NY State / Australia
  • Chardonnay / Riesling
55
Q

What are management options for fire? (3)

A

1) smoke detectors/sprinklers
2) installing water tanks
3) providing employee training in case of fire

56
Q

Identify 2 VIRUSES that can affect grapevines:

A

1) Fanleaf Virus
2) Leafroll Virus

57
Q

What is a management option for fanleaf virus (2)?

A
  • There is no cure = affected vines will have to be removed
  • before vineyards are planted, soil tests should be done to check for dagger nematodes + use nematode-resistant rootstock
58
Q

What is Phomopsis Cane / Leaf Spot?

How does it affect vines?

When is it particularly prevalent?

Examples of grapes that are MORE/LESS susceptible?

A

A fungal disease that causes reduction in crops

  • infected canes whiten and break off easily, shoots from these canes develop brown cracks at their bases.
  • Particularly prevalent in years w/cool, wet springs followed by humidity/moderate temps.

MORE susceptible: Grenache

LESS susceptible: Cabernet Sauvignon

59
Q

What is the main management option for phylloxera?

How does this method protect the vine?

What was the issue with using this method in Europe?

What was the solution to this?

A
  • grafting onto American rootstocks e.g. V. berlandieri, V. riparia.
  • When wounded, the roots form hard, corky layers that surround the eggs + seal wounds and protect from infection.
  • American rootstocks have little tolerance for lime, therefore struggled in calcareous European soils = suffered from chlorosis.
  • Solution was to create hybrid rootstocks that combined many different resistances e.g. phylloxera, nematodes, pH extremes, salinity etc…
60
Q

Identify 2 BACTERIAL diseases that can affect grapevines:

A

1) Pierce’s Disease
2) Grapevine Yellows

61
Q

What are management options for eutypa dieback? (5)

A

1) pruning late and applying fungicide to pruning wounds
2) cutting affected trunks back beyond symptoms and burning dead wood to prevent spores from spreading
3) re-training from “sucker” (shoot that grows from the base of a vine) but causes loss of yield for two years
4) Biological controls e.g. Bacillus subtilis
5) Removing vine + replanting

62
Q

What are management options for smoke taint? (5)

A

1) affected musts can be tested analytically to establish extent
2) how grapes are handled (since aroma precursors are present on inside of skins)
3) hand harvesting or gentle/whole bunch pressing, lower fermentation temperatures to reduce uptake of compounds.
4) flash detente (fast, heated maceration) / resverse osmosis.
5) blending with unaffected wines

63
Q

What are some options to do when frost threatens? (3)

A

1) water sprinklers (“aspersion”)
2) wind machines
3) oil/propane gas burning heaters

64
Q

What are management options for grey rot? (5)

A

1) selecting varieties with small berries / thick skins e.g. Petit Verdot
2) protecting grapes against pests that can split skins
3) keeping open canopy and removing leaves around bunches
4) sulphur and copper are ineffective but other fungicides can be used
5) Biological Control: antagonistic bacteria e.g. Bacillus subtilis.

65
Q

What is eutypa dieback aka?

What is it?

How are spores spread?

How does infection occur?

What will occur if not controlled?

A
  • aka “dead arm”
  • a fungal trunk disease that leads to rotten wood in vines and can affect whole vineyards
  • spores spread by wind over long distances
  • infection occurs through pruning wounds in moderate temperatures during rain
  • Reduces yield significantly, kills vines over 10-year period
66
Q

What causes Downy Mildew?

How does it affect vines?

What conditions does it thrive in?

A
  • caused by water mold Peronospora that lives in vine tissue
  • attacks green parts of plant, esp. young leaves+flowers, causes vines to defoliate = reduced yield.
  • needs rainfall and warm temperatures (20C / 68F) to spread (warm springs / stormy, warm summers)
67
Q

What are spider mites and what do they do?

What are 2 common examples?

What conditions do they thrive in, and when are they most damaging?

A
  • Mites which feed on the surface cells of leaves
  • leads to discolouration = reduction in photosynthesis, delayed ripening, yield reduction.

Pacific spider mite of California / Red spider mite of Europe.

  • They thrive in dusty conditions, most damaging when vines are water-stressed.
68
Q

What are management options for excess water? (2)

A
  • Plant on slope/free draining soil.
  • Construction of drainage system.
69
Q

What are management options for phomopsis cane / leaf spot (3)?

A

1) fungicides applied 3 weeks after bud burst, continue if wet weather persists.
2) diseased wood removed/burnt
3) best to prune early/late and not in rainy weather

70
Q

What are management options for sunburn? (5)

A

1) row orientation and aspect (avoiding east-west orientation in hot climates in N. Hem. to avoid intense afternoon sun)
2) canopy management techniques to control amount of direct sun exposure
3) irrigation to reduce water stress/sunburn
4) agricultural sunscreen
5) cloth/net shading

71
Q

What is fanleaf virus (1) and how is it spread (3)?

AKA?

A
  • long standing group of diseases found around the world
  • spread by move to grafted vines, inadvertent use of infected plants and dagger nematode

AKA Fanleaf degeneration

72
Q

What is leafroll virus?

How does it affect vines (3)?

Where is it particularly prevalent (5)?

A
  • Group of viral diseases spread by grafting and mealy bugs
  • doesn’t kill vines but can reduce yield by up to half by slowing down growth of roots and shoots.
  • Surviving fruit takes additional weeks to ripen, reducing quality (more acid, less sugar+color)
  • Overall health of the vine declines as it stores less carbs.

Humid environments which are favorable to mealy bugs: S. Africa / Mediterranean / Argentina / California

73
Q

What are the 3 most common types of Grape Moths?

Identify a recent incident of Grape Moth infestation via inadverdent importation:

A

1) Light brown apple moth of Australia.
2) European grapevine moth.
3) Grape berry moth of N. America.

2009 infestation of European grapevine moth in Napa Valley (eradicated in ‘16)

74
Q

Explain how Water Sprinklers (aka “aspersion”) protect vines fom frosts:

What are the pros(1)/cons(2)?

A
  • Water freezes around plant and releases latent heat.

PROS: Cost can be lower than wind machines/heaters.

CONS: - Must be kept on until temperature rises again.

  • Costs of equipment/water.
75
Q

What does downy mildew look like?

A

Yellow, circular “oil spots” on leaves and then white, downy fungal growth on underside of leaves

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