Pests in the Vineyard Flashcards
Explain Phylloxera and its effect on the vine.
This aphid-like insect feeds on and lays eggs on the roots of grape vines. It weakens vine roots and causes swellings and cracks, which then lead to rot. The insects can spread through crawling and flying and are commonly transported by humans, for example, on the roots of young vines, in soil, on equipment such as leaf trimmers and harvesters and by irrigation water.
What are the symptoms of Phylloxera?
Symptoms of phylloxera infestation are:
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
What are the management options for Phylloxera?
The use of American vine species, especially V. berlandieri, V. riparia and V. rupestris, which offer most protection. These species form hard, corky layers that surround the eggs, sealing the wounds and preventing invasion by bacteria or fungi. Rootstock hybrids between the various American species balance the level of protection to phylloxera and resistance to lime in the soil.
Planting on rootstocks is significantly more expensive than on the vines own roots, but has become a standard part of the cost of establishing a vineyard.
Explain Nematodes and their effect on the vine
Nematodes, tiny worms, are very common in soils, but are usually too small to be seen by the naked eye. Some cause damage by feeding off vine roots, significantly reducing yields and vigour. They can cause slow, gradual decline. Others transmit viral diseases. For example, fanleaf virus is spread by the dagger nematode.
Two of the most commonly occurring are root-knot nematode and dagger nematode. Nematodes are either present in the soil already or can be spread by unclean nursery stock, irrigation water or vehicles. Once present, they can only be managed, not eliminated.
What are the management options for Nematodes?
(Soil samples are taken and analysed in a laboratory to determine the number and type of nematodes present.)
Management options:
Leave the soil fallow for a number of years, but this is very expensive as no crop is produced.
Fumigate the soil. Chemicals used to be used, but these are now banned in most regions. Another method is to 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.
Explain Grape Moths and their effect on the vine.
A number of different moths do damage to vines by feeding on flowers and grapes. Many species have several generations per season, attacking flowers in spring and grapes later in the year. The wounds created are then vulnerable to further attack from bacteria and fungi, including botrytis, and significant crop losses have been reported. The most common types are the light brown apple moth in Australia, the European grapevine moth in southern Europe and the grape berry moth in central and eastern North America.
What are the management options for Grape Moths?
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).
Insecticides can be used.
Explain Spider Mites and their effect on the vine.
Several types of mites can damage vines, but spider mites are the most detrimental. The species of spider mite differs from region to region. Pacific spider mite is most destructive in California. In Europe the red spider mite and two forms of yellow spider mite can cause damage. They feed on the surface cells of leaves. This leads to discoloration of the leaves, a reduction in photosynthesis, delayed ripening and a reduction in yields. Spider mites thrive in dusty conditions and are most damaging when vines are already water stressed.
What are the management options for Spider Mites?
Make the environment inhospitable by the use of water sprinklers and/or cover crops or mulches to reduce dust.
Encourage predatory mites (by planting host species) that feed on spider mites.
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.
Explain birds effecting the vine
Birds can be a serious threat to vine growers as they destroy an entire crop of grapes as they ripen. Isolated vineyards that provide the only source of food in an area are particularly in danger. In addition to physical damage to grapes, bird damage allows bacteria and fungi to enter bunches, which leads to rot. Starlings are one species that often attack vineyards.
What are the management options for Birds?
The cost of total netting can be justified in high value areas (for example, Mornington Peninsula in Australia) or where birds are a major threat.
Other measures such as bird scarers or noises can be used, but must be rotated regularly to avoid the birds getting used to them. Falcons are sometimes used to deter unwanted bird visitors.
Explain mammals effect on the vine
Mammals can do damage in vineyards by eating shoots, grapes and leaves, by breaking the skins of grapes, and thereby making them vulnerable to rot, and by damaging structures such as trellising. They thus reduce yield, lower the quality and introduce extra cost in repairing the damage. A range of animals are pests in different parts of the world. These include deer, rabbits, kangaroos, raccoons, wild boar and baboons(S.Africa).
What are the management options for Mammals?
Mammals can be kept out by fencing but these have to both be sufficiently high and sunk into the soil to stop burrowing animals.
