Diseases Flashcards
What is oidium also known as?
Powdery Mildew
Where is generally the only fungus found?
California
What type of weather does oidium like for germination?
Cooler weather
What temperature is ideal for rapid development of oidium?
70-90F
What does oidium attack?
Leaves and fruit
What prevents oidium?
sulfur dust
What vinifera grapes are most susceptible to powdery mildew?
Carignane, Muscat of Alexandria, Sylvaner
How does downy mildew germinate?
In a film of water on the vines
What does down mildew affect earlier in the year?
Leaves, tendrils, berry clusters, petioles, shoots.
Which vinifera are most susceptible to downy mildew?
Chardonnay, Riesling
What is the most effective treatment for downy mildew?
Bordeaux mixture
What are the ingredients of Bordeaux mixture?
Copper sulfate
Slaked lime
Table salt
Water
Where is Black Rot most dangerous in the US?
East
In what kind of weather does black rot germinate?
Warm, humid weather
What does Black Rot attack?
leaves
What is an effective combatant to Black Rot?
Bordeaux mixture
How does Black Rot initially look on a vine?
As black spots on the vines shoots, leaves and berries.
What causes Black Rot?
The Guignardia bidwelli fungus
How did black rot spread to Europe?
With the importation of phylloxera-resistant rootstocks in the late 1800s.
Where is Black Rot native to?
North America
When does Noble Rot develop?
Later in the season
What is noble rot known as in Germany? In Italy?
Edelfaule, Muffa
Why is later day dry weather vital to good wine, with regards to noble rot?
If there is unrelenting heat and dryness, then the fungus will not actually develop, and grapes will accumulate sugar, rather than undergoing the chemical transformations associated with noble rot. But the medium of warm, sunny, dry days after the moisture will create the idea growing conditions.
What is the color transformation of grapes infected with the noble rot?
Golden -> pink or purple -> brown
How does botrytis affect these 3 factors of a grape?…
Sugar
Tartaric Acid
Malic Acid
Sugar - Decrease by 1/3
Tartaric Acid - Decrease by 5/6
Malic Acid - Decrease by 1/3
What does botrytis form in a grape?
Glycerol, acetic acid, gluconic acid, laccase, pectinase, other enzymes, botyticine (a yeast-inhibiting glycoprotein).
What is glycerol?
A polyol and minor product of fermentation, usually present from 5-12 grams/liter, but in botrytized wines up to 25 g/l.
At what temperature does Noble Rot grow best?
65-75 (18-24)
What do vines infected with Eutypa Dieback experience?
Stunted shoot growth, as the fungus releases toxins, and potentially causes the death of a cane.
What does Eutypa Dieback primarily affect?
yield
How does Eutypa Dieback enter the vine?
carried by rain, entering the vine through pruning wounds.
What causes Eutypa Dieback?
The Eutypa lata fungus
What is Eutypa Dieback also known as?
Dead Arm
Esca-infected vines rarely live past what?
30 years of agents
What can Esca do to older vines?
It affects the wood, causing the interior of the trunk and arms to soften and rot from the inside.
What does Esca do to young vines?
Weaken growth, affect berry development and discolor leaves. Death may occur in hot weather.
Where does Esca thrive?
warmer climates
What is Esca also known as?
What kind of disease is it?
Black measles
Fungal
What does downy mildew cause?
Dropping of vine leaves, which limits the vine’s ability to photosynthesize.
What is the agent of downy mildew?
Plasmopara viticola
What can mealy bugs of the genera Planococcus and Pseudococcus spread?
Leafroll virus
What are some indirect effects of mealybug’s sap sucking?
They produce a lot of “honeydew” which collects over the bunches and foliage, and on which fungus grows, often giving it a sooty appearance.
When and where was the first vine mealy bug indentified?
California’s Coachella Valley in the early 1990s
Mealy bugs prefer a _____ environment.
humid
When do mealy bugs become mature and reproduce?
early summer
Which mealy bug can feed on roots?
Planococcus ficus
What are mealy bugs and what do they do?
Small white insects of the family Cicadellidae which suck vine sap, infect new growth in the spring, typically at the undersurface of the leaves.
What are phytoplasmas?
Pathogens similar to bacteria, yet symptomatically similar to viral diseases.
How are viral diseases spread in the vineyard.
Through grafting or from transmission from insects.
What climates are fungal diseases typically associated with?
warm and damp climates
How do fungal diseases manifest?
As mildew or mold
What is powdery mildew?
aka oidium
A fungal disease native to North America, spread to France & noticed in 1847. Green parts of the vine are attacked, and a cobweb like growth spreads. Ash-like spores soon show up on short, upright stalks.
What are examples of agrochemicals?
fungicides, insecticides, herbicides, bird repellents, plant growth regulators, rodenticides, soil fumigants
A common feature of vineyards with a reputation for producing high-quality wines is that they are of _____ vigor, and that the canopy microclimate is characterized by _____ and _____ shade.
- moderate to low
- good exposure of leaves and fruit to the sun
- little
What is the full two names for phylloxera?
Phylloxera Vastatrix
Phylloxera the destroyer
What does phylloxera attack? What does this cause?
The vines…it lowers the sap pressure level.
How are those affected vines vulnerable?
New pathogens can attack the vine
What is Millerandage?
It affects big variation in grape size
What grapes are affected by millerandage?
Gewurztraminer, Chardonnay 1a & Mendoza clones
What is couloure?
Failure of grapes to develop after flowering
When does couloure usually happen?
Spring
Why does couloure happen?
The vine is trying to conserve resources
What grapes are prone to couloure?
Grenache, malbec, merlot, muscat ottonel
What is Crown Gall also known as?
Agrobacterium Tumefaciens
Where and when does crown gall happen?
On vines injured by winter freeze
What transmits the bacteria that causes Pierce’s Disease?
Glassy winged sharpshooter
What is the bacteria that causes Pierce’s Disease?
Xylella Fastidiosa
