Viticulture Flashcards
What is the scientific name for powdery mildew?
Oidium (uncinula necator)
What is powdery mildew?
It infects all green parts of the plants and affects all green parts of the plants marking grapes leaves and shoots with dusty white mildew growth.
What can prevent powdery mildew?
Application of sulfur and other fungicides is used for control and prevention.
What happens if powdery mildew occurs prior to flowering?
Yields will be reduced.
What happens if powdery mildew affects the plants after fruit set?
The berries will struggle to achieve veraison and reach full size.
Name some fungal diseases.
Powdery Mildew Downy mildew Esca Eutypa Dieback Black Rot
How does powdery mildew occur?
The disk disease develops and spreads most rapidly in warm weather does well in dry weather and is a spread by dry winds. The spores develop in the winter time.
What is Downy mildew?
A spore called zoospore swims and needs moisture to germinate and infect and infection occurs when the downy spores move from the soil to the vine.
What type of conditions encourage the development of downy mildew?
Warm, humid springs and summers and is more prevalent with these conditions in Northern Europe
How can downy mildew affect the plant?
If severe, the leaves will drop off which then creates the loss of photosynthesis, causing delays in fruit ripening and levels of fruit sugar. Bud break and early shoot growth can be delayed the following Spring.
How is downy mildew contained?
Downy mildew is controlled organically with various preventative copper sprays, Phosphorous acid can also help.
What is esca?
Esca is a fungal disease that effects the wood of the vine and is more likely to affect old vines those at least 10 years old.
What is bunch rot?
AKA berry rot is caused by many species of yeasts and bacteria. Promoting good air circulation and sunlight exposure within the grapevine canopy reduces the risk. Pulling the leaves is also helpful.
What is Eutypa Dieback?
AKA Dying Arm or Dead Arm. A disease caused when spores shoot into the air during rain events and infect vines through the wood through fresh pruning wounds, working their way into the vines, choking off the sap and eventually killing the vine.
How is Eutypia Dieback diagnosed?
It can easily be diagnosed in the Spring: young shoots are stunted and yellow with small misshapen cupped leaves caused by toxins in the infected trunks and/or arms.
Removing the infected arms and trunks may help the vine.
What is black rot?
A disease caused by the fungus, Guignardia bidwelli which attacks young shoots, leaves, stems, and berries and spreads in only mild, wet weather.
It is controlled with fungicides sprayed from spring up to fruit ripening and removing the infected berries from the vineyard.
What is Daktulosphaira vitifoliae?
Phylloxera
How does Daktulosphaira vitifoliae affect the vine?
It feeds on the roots of the vine resulting in deformation and destroying the root system.
How are the vines protected from Daktulosphaira vitifoliae?
Vines are grafted onto American rootstock such as Vitus riparia to prevent phylloxera’s effect.
What major wine producing country is the one that is totally free from Phylloxera?
Chile
What are phytoplasmas?
Small and sometimes microscopic organisms similar to bacteria associated with diseases of the phleom (food-conducting tissue of the vine) transmitted by insects and grafting.
What are grapevine yellows?
A generic term for a group of related phytoplasma diseases of grape vines which poses a big threat to vines.
How are phytoplasma diseases introduced to the vine?
Pathogens similar to bacteria spread through an insect vector or rootstock grafting.
Generally speaking, which can be more devastating? Bacterial or viral disease?
Bacterial
How do viral diseases infectt the Vine?
Viral diseases spread through grafting or transmission by insects. There is no known cure for many common viral infections but they can be partially controlled by removal of appropriate sections of the Vine for propagation of new healthy vines.
Fungal diseases are manifested as what 2 things?
Mildew or mold
What climates are fungal diseases most prevalent in?
Warm and a damp climates are most conducive to these
What parts of the Vine do fungal diseases affect the most?
The root system or the canopy
What are the 4 categories of disease a Vine may be subject to?
Fungal
Bacterial
Viral
Phytoplasmic
Cordon de Royat and Geneva are examples of what kind of training?
Cordon training
With cordon de royat and Geneva training, which is most similar to Guyot? How is it different than Guyot?
Cordon de Royat but there’s a single spur pruned permanent cordon extending from the trunk rather than a 2 year old cane.
What is the trellising system that is widely used in Bordeaux (reds) and California (Napa Valley Cabs)?
Guyot