Pests Flashcards
What is phylloxera?
- 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.
Five main symptoms of phylloxera:
- Vines die of drought in patches that increase in size year by year
- Vine roots are covered with the insects surrounded by yellow eggs
- Swellings on older roots
- Pale green leaf galls on the under-surface of the leaves
- Slow, stunted shoot growth and leaf yellowing appears in around three years, the plant dies after around five years.
Effect of phylloxera on Europe.
Destroyed two-thirds of the European vineyard in the late nineteenth century.
Three management options for phylloxera:
- Planting American vine species
- Grafting European varieties onto rootstocks from single American vines
- Grafting European varieties onto rootstocks hybrids from multiple American vines (the best option)
Three American vine species that offer the most protection against phylloxera.
- V. berlandieri
- V. riparia
- V. rupestris
How do the American vine species protect against phylloxera?
They form hard, corky layers that surround the eggs, sealing the wounds and preventing invasion by bacteria or fungi.
Issues with grafting onto the rootstocks of single American varieties.
- 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.
How to choose rootstock.
- 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:
- the vineyard soil
- the pests to be combatted
- the level of vigour desired
What are nematodes?
Tiny worms that live in the soil, typically too small to be seen by the naked eye.
How are nematodes harmful to vines?
- Feed off vine roots
- Transmit viral diseases
Two common vineyard nematodes:
- Root-knot nematode
- Dagger nematode
How do nematodes spread?
- present in the soil already
- unclean nursery stock
- irrigation water
- vehicles
How are nematodes managed?
- 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.
- The best solution is the use of nematode-resistant rootstocks
Describe how grape moths affect vines.
- 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
Three common types of grape moths and where you find them.
- Light brown apple moth (Australia)
- European grapevine moth (southern Europe)
- Grape berry moth (central and eastern North America)
