Vine pests Flashcards
Name 5 natural hazards that threaten vine growing
1) drought
2) excess water
3) untimely rain
4) fire
5) smoke taint
6) hail
7) frost
8) Freeze (-20C)
9) Sunburn
Name the 2 different types of frost
1) Advective- comes from elsewhere, brought in by wind
2) radiative - heat loss. No wind means the air can settle
Name 4 risk reduction methods for protecting against frost
1) Site selection (frost pockets)
2) Slopes - cold air rolls down the hill
3) Varietal choice
4) proximity to a body of water (further away is better)
5) bare soils which absorb more heat during the day and consequently radiate more at night
6) Trellis higher to avoid ground frost
What is the only combative method for advective frost (frost coming in from colder areas)
Sprinklers ; as the water around the plant freezes, it gives off latent heat which protects the plant.
What rootstock is more resistant to freeze
amurensis
What is the impact of smoke taint after veraison
The impact is worse as the smoke gets under the skin. The smoke particles bind to sugars, and the taint only manifests itself after fermentation, and gets worse with age.
What maceration process can help alleviate the effect of smoke taint
Flash detente where the wine is heated very quickly
Reverse osmosis also works but is expensive.
What hazard would you mitigate against with nets and insurance
hail
Downside of nets is they shade the vines. This isn’t a problem in hot sunny regions such as Mendoza.
Describe the symptoms of phylloxera
- drought patches increasing every year
- insects on roots with yellow eggs
- bulbous roots
- leaf galls on underside of leaf
- stunted growth & leaf yellowing (after 3 yrs)
- death after 5 years.
What can be done to mitigate against phylloxera
- sandy soils
- choice of rootstock : Riparia, Rupestris and Berlandieri
But you need hybrids so they’re tolerant of chalk / limestone soils
How can you manage nematodes in the soil
- tests to work out number / type of nematode in soil
- mustard plant as a biofumigator
- rootstocks: Champini (dog ridge and Ramsey) both resistant.
Do grape moths eat the fruit, the leaves, the flowers or the shoots of the plant?
leaves and flowers.
What damage to grape moths inflict on the plant
open wounds where they feed which are an infection risk.
What are natural predators of grape moths
wasps, green lace wings, spiders
What damage do spider mites inflict on the plant
They eat the surface cells of the leaves which inhibits the plant’s ability to photosynthesise
How do you manage against mites
- reduce dusty conditions
- introduce predatory spider mites
- use pesticides, either specific ones (expensive) or generic ones (might kill natural predators)
How do you deter birds
netting
falcons
music / scarecrows (need to be changed frequently)
Name three fungal diseases that attack vines
1) grey rot - Botrytis cinerea
2) powdery mildew - oidium tucheri - the Erysiphe Necator fungus
3) downy mildew - Peronospora
4) Eutypa dieback
5) Phomopsis cane & leaf spot
6) Esca
Which fungus doesn’t need humidity to thrive
powdery mildew. It likes 25C, shade and dry temperatures.
What happens to powerdy mildew over winter.
Nothing - it lies dormant on the plant and then eats green shoots in spring.
Ho can you manage powdery mildew
Shade management (reduce shade) and spraying. Copper works, but washes off in the rain, resulting in more sprays needed (And a risk of heavy metals in the soil), so conventional spraying also used.
What is the issue of using fungicides
1) not allowed in organic or BD farming
2) the fungus adapts and the sprats become ineffective.
What are the symptoms of powdery mildew
grey patches turning black, and grapes split at veraison
What is the main risk of downy mildew
defoliation
What conditions are favourable to downy mildew
20C + rain
What are the symptoms of Downy mildew
yellow “oil” spots on leaves and then downy fungus underneath.
How do you manage downy mildew
canopy management (air flow) and spraying (CUSO4)
What activates grey rot
rain
what does grey rot attack
the fruit. in particular vulnerable fruit (eaten by grape moths, attacked by birds, split grapes…)
How can you fight grey rot
bacillus subtilis or spraying at key moment (end of flowering, bunch closure and veraison)
spray with fungicide. CU doesn’t work
Pick grapes with thick skins
What does Eutypa dieback, or deadarm, attack on the plant?
The wood. It attacks the trunk. Infected wood needs to be cut off and burnt to kill the spores
How does Eutypa dieback spread?
pruning wounds, and is spread by wind. Prevalent in the rain.
What does Phomopsis attack
the canes: they whiten, crack and then fall off.
What conditions are favourable to the promotion of phomopsis
cool spring and lots of humidity
How do you manage phomopsis
Spraying after bud burst, then every 2 weeks if damp.. Cut and destroy affected and dead wood
reduce humidity with canopy management
Which fungal disease leads to tiger striped leaves
Esca
What causes Esca to spread
pruning wounds. Avoiding pruning in the rain
Name the two main bacterial diseases that affect vines
Pierce’s diseases and Grapevine Yellow
How do you combat Pierce’s disease
you can’t - you can just try and avoid it. It is spread by sharpshooters, so moving away from their habitats (riverbeds) or installing natural predators such as wasps can help.
Where would you find the bacteria that causes Pierce’s disease
in the sap channels. They clog them, killing the plant.
What spreads grapevine yellows
Leafcutter insects
What are the symtoms of grapevine yellows
Delayed bud burst, yellowing leaves (or red in black varieties), dropping stalks (they don’t go woddy)
What 2 viruses are a threat to vines
leafroll land fanleaf
Which is spread by the dagger nematode
Fanleaf. Leafroll is spread by grafting and mealy bugs.
Which of the two, leaf roll or fan leaf, kills the plant
leafroll. Fanleaf is bad for faulty but doesn’t kill the plant.
What damage does the phylloxera louse inflict on viniferas plants
Feeds on the roots, removing photosynthates (starch and sugar) and leaving open wounds which are susceptible to attack from bacteria and fungi which further attack the root structure.
In American vines, the phylloxera louse lays its eggs (predominantly) on the leaves rather than the roots. How can you tell an infected plant?
Raised, wart-like lumps, reddish brown in colour called “galls” which contain the eggs.
When was phylloxera first seen in Europe
1863 in uk. First mainland European sighting was near Avignon the same year (planted in 1861). 1872: the Douro 1879: Italy 1890: champagne (last vine yards)
What species and what rootstocks are resistant to nematodes
Species: champini & longii
Rootstocks: dogridge, freedom, harmony and Ramsey
What causes chlorides?
Lime rich soils
High levels of calcium carbonate lock up the iron which is needed to produce chlorophyll essential for photosynthesis
Which rootstock has high chlorosis tolerance?
Berlandieri
