8.2 Pests

Question 1

What is phylloxera?

Answer 1

• Aphid-like insect that feeds on and lays eggs on the roots of grape vines.
• Weakens vine roots and causes swellings and cracks, which then lead to rot.

Question 2

How does phylloxera spread?

Answer 2

• Crawling
• Flying
• Transported by humans

Question 3

What are the 5 main symptoms of phylloxera?

Answer 3

1. Vines die of drought in patches that increase in size year by year
2. Vine roots are covered with the insects surrounded by yellow eggs
3. Swellings on older roots
4. Pale green leaf galls on the under-surface of the leaves
5. Slow, stunted shoot growth and leaf yellowing appears in around three years, the plant dies after around five years.

Question 4

When was phylloxera identified? Where? Where did it originate?

Answer 4

• Identified: 1863
• Identified in: Europe
• Originated in: USA

Question 5

What was the effect of phylloxera on Europe?

Answer 5

Destroyed two-thirds of the European vineyard in the late nineteenth century.

Question 6

What was the effect of phylloxera on USA?

Answer 6

Nothing. American species were naturally resistant.

Question 7

What types of soil is immune to phylloxera?

Answer 7

Sandy

Question 8

What are management options for phylloxera?

Answer 8

1. Planting American vine species (not ideal)
2. Grafting European varieties onto rootstocks from single American vines (not ideal)
3. Grafting European varieties onto rootstocks hybrids from multiple American vines (ideal)

Question 9

Name the 3 American vine species that offer the most protection against phylloxera.

Answer 9

• V. berlandieri
• V. riparia
• V. rupestris

Question 10

Describe how the American vine species protect against phylloxera.

Answer 10

They form hard, corky layers that surround the eggs, sealing the wounds and preventing invasion by bacteria or fungi.

Question 11

Why aren’t American vine species typically used? What are they typically used for?

Answer 11

They produce different and undesirable aromas in the resulting wine. The solution was to graft European varieties onto rootstocks from American vines.

Question 12

What tends to happen when grafting onto the rootstocks of single American varieties? Why?

Answer 12

• Soils of Europe are typically calcareous
• American varieties have little lime tolerance
• Thus, vines suffered from chlorosis turning the leaves yellow, halting photosynthesis and reducing yields and quality

Question 13

How does one choose which rootstock to use?

Answer 13

• There are many rootstocks, often with complex parentage, that can deal with a number of problems
  (phylloxera, nematodes, extremes of soil pH, water stress, salinity)
• Goal is to match the appropriate rootstock to:
  1. the vineyard soil
  2. the pests to be combatted
  3. the level of vigour desired

Question 14

What is a main disadvantages of planting on rootstocks?

Answer 14

Significantly more expensive than on the vines own roots

Question 15

What are nematodes?

Answer 15

Tiny worms that live in the soil, typically too small to be seen by the naked eye.

Question 16

How are nematodes harmful to vines?

Answer 16

• Feed off vine roots

- Transmit viral diseases

Question 17

Name 2 of the most commonly occurring nematodes.

Answer 17

1. Root-knot nematode

2. Dagger nematode

Question 18

How do nematodes spread?

Answer 18

• present in the soil already
• unclean nursery stock
• irrigation water
• vehicles

Question 19

How can nematodes be eliminated?

Answer 19

They can’t. They can only be managed.

Question 20

How are nematodes managed? What happens first? What is typically the best solution?

Answer 20

Soil samples are analysed in a lab to determine the number and type of nematodes present.

• Leave the soil fallow for a number of years (costly, no crop)
• Fumigate the soil.
• Plough in a cover crop of mustard plant, which contains compounds that work as biofumigants, killing nematodes.
• For most, the best solution is the use of nematode-resistant rootstocks

Question 21

What are grape moths and how do they affect vines?

Answer 21

• Many species of moths that feed on flowers and grapes, damaging vines
• Wounds created are then vulnerable to further attack from bacteria and fungi, including botrytis

Question 22

Name the 3 most common types of grape moths and the regions they affect.

Answer 22

• Light brown apple moth (Australia)
• European grapevine moth (southern Europe)
• Grape berry moth (central and eastern North America)

Question 23

What happened to Napa Valley in 2009?

Answer 23

• European grapevine moth was introduced accidentally

- Eradicated in 2016

Question 24

How are grape moths managed?

Answer 24

1. Biological controls include the use of:
   - - the bacterium Bacillus thuringiensis (which produces substances that are toxic to the moths)
   - - use of pheromone capsules to disrupt mating (‘sexual confusion’)
   - - natural predators (parasitic wasps, green lacewings, some spider species).
2. Insecticides can be used.

Question 25

Describe the effects of spider mites on vines.

Answer 25

They feed on the surface cells of leaves: - - Discoloration - - Reduction in photosynthesis - -- Delayed ripening - -- Reduction in yields Vary from region to region

Question 26

Name the most common types of spider mites and the regions they affect.

Answer 26

- Pacific spider mite (California) - Red spider mite (Europe) - Two kinds of yellow spider mite (Europe)

Question 27

Where do spider mites thrive?

Answer 27

Dusty conditions

Question 28

When are spider mites the most damaging?

Answer 28

When vines are already water stressed

Question 29

How are spider mites managed?

Answer 29

1. Reduce dust: Make the environment inhospitable by the use of water sprinklers, cover crop, mulches 2. Encourage predatory mites (by planting host species) that feed on spider mites. 3. General pesticides may kill beneficial predatory mites. Specific sprays can be applied to kill only the mites that are problematic in the vineyard, but this can add to costs.

Question 30

Name 2 other insect pests and how they damage vines.

Answer 30

1. Leafhoppers (they cause direct damage to vine leaves) | 2. Ladybirds (which can cause taints to the wine if they are amongst harvested grapes)

Question 31

Why can birds be can be a serious threat to vine growers?

Answer 31

- They feed on an entire crop of grapes as they ripen | - Damage allows bacteria and fungi to enter bunches, which leads to rot.

Question 32

What vineyards are most in danger of birds?

Answer 32

Isolated vineyards that provide the only source of food in an area

Question 33

Name 1 species of bird that often attack vineyards.

Answer 33

Starlings

Question 34

What are the management options for birds?

Answer 34

1. Netting - Costly | 2. Bird scarers or noises (must be rotated so birds don't get used to them) - Falcons

Question 35

Why can mammals be can be a serious threat to vine growers?

Answer 35

- Eating shoots, grapes and leaves - Breaking the skins of grapes (vulnerable to rot) - Damaging structures such as trellising

Question 36

Name some examples of animal pests in different parts of the world.

Answer 36

- Deer - Rabbits - Kangaroos - Raccoons - Wild boar - Baboons

Question 37

What is the main management option for mammals?

Answer 37

Fencing | - Must be sufficiently high and sunk into soil (for burrowing animals)