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

What are the five main symptoms of phylloxera?

Answer 2

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 leaves
5. slow, stunted shoot growth and leaf yellowing appears in around three years, then the plant dies after around 5 years

Question 3

Effect of phylloxera on Europe?

Answer 3

destroyed two-thirds of the European vineyards in the late 19th century

Question 4

Three management options for phylloxera:

Answer 4

1. planting American vine species
2. grafting European varieties onto rootstocks from single American vines
3. grafting European varieties onto rootstock hybrids from multiple American vines (the best option)

Question 5

Three American vine species that offer the most protection against phylloxera:

Answer 5

1. V. berlandieri
2. V. riparia
3. V. rupestris

Question 6

How do American vine species protect against phylloxera?

Answer 6

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

Question 7

Issues with grafting onto the rootstocks of single American varieties?

Answer 7

• 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 8

How to choose rootstock?

Answer 8

• 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)

The goal is to match the appropriate rootstock to:

1. the vineyard soil
2. the pests to be combatted
3. the level of vigor desired

Question 9

What are nematodes?

Answer 9

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

Question 10

How are nematodes harmful to vines?

Answer 10

• feed off vine roots
• transmit viral diseases

Question 11

Two common vineyard nematodes:

Answer 11

1. root-know nematode
2. dagger nematode

Question 12

How do nematodes spread?

Answer 12

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

Question 13

How are nematodes managed?

Answer 13

• 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 act as biofumigants, killing nematodes
• the best solution is the use of nematode-resistant rootstocks

Question 14

Describe how grape moths affect vines.

Answer 14

• 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 15

Three common types of grape moths, and where you find them:

Answer 15

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

Question 16

How are grape moths managed?

Answer 16

1. biological controls, including:

• the bacterium Bacillus thuringiensis (provides substances that are toxic to moths)
• use of pheromone capsules to cause sexual confusion and disrupt mating
• natural predators (parasitic wasps, green lacewings, some spider species)

2. insecticides

Question 17

Effects of spider mites on vines?

Answer 17

The feed on the surface cells of leaves:

• discoloration
• reduction in photosynthesis
• delayed ripening
• reduction in yields

Question 18

Three common types of spider mites and where you can find them:

Answer 18

• Pacific spider mite (California)
• red spider mite (Europe)
• two kinds of yellow spider mite (Europe)

Question 19

When are spider mites most damaging?

Answer 19

When the vines are water stressed, drought

Question 20

Three ways to manage spider mites:

Answer 20

1. reduce dust: make the environment inhospitable by the use of water sprinklers, cover crop, mulches
2. encourage predatory mites (by plating 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 21

Why are birds a threat to growers?

Answer 21

• they feed on grapes as they ripen
• damage allows bacteria and fungi to enter bunches, which leads to rot

Question 22

Management options for birds:

Answer 22

• netting
• scarers

Noise, light, predators

Question 23

Risks of mammals to growers:

Answer 23

• eating shoots, grapes, and leaves
• breaking the grape skins, vulnerable to rot
• damaging structures such as trellising

Question 24

Examples of mammal pests in vineyards:

Answer 24

• deer
• rabbits
• kangaroos
• raccoons
• wild board
• baboons

Question 25

Management options for mammals:

Answer 25

- fencing - scarers