Viticulture: wine grapes Flashcards
Why are grape berries the ideal medium for fermentation?
They are high in sugar and contain other nutirents for yeast metabolism
What type of plants are grapes
- Woody perennial - hard stem made of wood tissue that does not die back each year.
- Desiduous - lose their leaves each year
- A vine (or liana) - can climb support systems
What is the genus and specaies of wine grapes?
Vitus Vinefera
(used for most wine production)
thousands of varieties identitifed
Where does the word cultivar come from?
“cultivatied variety”
Where do wine grapes grow best?
region of lat & long
between 30 degrees and 50 degree latitiude in northern and southern hemispere
In what climate do grapes best grow?
Temperate climates of between 10-20 degreec celsius
Long growing season of 6-7 months
What are the most common grapes varieties grown worldwide?
- Cabernet Sauvignon
- Merlot
- Tempranillo
- Airen
- Chardonnay
What compaound gives grapes their skin color?
- Anthocyanin
- contact time between juice and skin give wine its color
Why are north american grape varieties important to wine?
rootstocks resistant to Phylloxera
- Vitis Rupestris
- Vitis Riparia
What are the two aproaches to addressing Phylloxera?
- Hybrids - chosing different varieties to produce hybrids.
- Rootstocks - using resistant rootstocks for grafting
Why is rootstock grafting preferred to hybridization for Phylloxera?
Hybrids can produce undeirable flavors for wine making
What is Phylloxera?
an insect that feeds on the rootstocks of grape vines, eventually killing the vine.
What is powdery mildew?
- A fungal disease
- white powdery appearance
- prone in warm, humid environments
What is Botrytis Cinerea?
- A fungal disease (noble rot)
- cracks the grapeskin making it susceptible to other infections, like acetobacter
- prone in warm, humid climates
Noble Rot creates desirable flavors for dessert wines, like Sauternes
How are fungal diseases treated?
- sulfur powders
- copper sprays (Bordeaux mix)
- fungicides
What is Pierce’s disease?
- Bacterial disease spread by insects
- Blocks the flow of sap, eventually killing the vine
controlled by controlling insect vectors
What is Leafroll?
- viral disease spread by insects
- decreases sugar content and pigment of the berries
What is Red Blotch?
- viral disease
- delays berry ripening and decreases sugar levels
How are viral diseases controlled?
- use clean plant materials
- control insect vectors
