Viticulture Flashcards
How can spider mites be managed?
- sprinklers or cover crops to reduce dust
- predatory mites
- pesticides
What is the optimal temperature for germination?
79 - 90 degrees F
How is leafroll virus spread?
Unclean grafting and mealybugs
What is the optimal temperature range for photosynthesis?
64 - 91 degrees F
What causes downy mildew (peronospersa)?
- water mold living in vine tissue
- warm springs and rainy, warm summers
What is the optimal temperature for vine flowering?
63 degrees F
Describe Esca?
- complex fungal disease caused by a group of organisms
- favors warm, dry climates
- enters through pruning wounds
- tiger striping on leaves
- reduces yield, kills in a few years
What are the symptoms of Pierce’s Disease?
- bacteria clogs sap channels
- shrivels grapes
- drops leaves
- kills between 1 to 5 years
What are the symptoms of grapevine yellows?
- delayed budburst
- droopy shoots
- failure of shoots to lignify
- leaves turn yellow or red
How is Fanleaf virus transmitted?
nematodes
How is Pierce’s disease spread?
Glassy winged sharpshooter
How does Eutypa dieback attack a vine?
through pruning wounds
How is oidium best managed?
- keep open canopy
- sulfur treatments
What are the visual symptoms of downy mildew?
- oil spots and white downy growth on leaves
- defoliation
What are the symptoms if powdery mildew?
- dull grey or black patches on leaves
- reduces yield
How are grapevine yellows spread
insects
How is Pierce’s Disease managed?
- no cure but insecticides may help
- remove vine from insect habitats
- predatory wasps
- quarantine exposed plants
How is leafroll virus managed?
- no cure, remove vine
- screen for virus in nurseries
- reduce mealybug populations via open canopies and predatory insects
Leafroll and Fanleaf are what type of diseases?
viral
What are the visual symptoms of phylloexera?
- insect eggs on vine roots
- pale galls on leaves
- stunted growth
- yellow leaves
- vine death
How is downy mildew managed?
- open canopy
- good drainage
- Bordeaux mixture (copper sulfate and lime)
What is the most common grapevine yellow disease?
Flavescence doree
What are the symptoms of fanleaf virus?
- stunted growth
- distorted canes
- pale, deformed leaves
What are 2 synonyms for gobelet training?
- albarello
- en vaso
- gobelet
What are the symptoms of leafroll virus?
- reduces yield and quality
- slows growth of roots and shoots
- slows ripening
- more acidic grapes with less color and sugar
- downward turned red or yellow leaves
What is the minimum amount if sunshine hours needed to support viticulture?
1300 hours
What type of pruning is easiest for mechanization?
spur pruned
What is the optimal temperature range for the synthesis of anthocyanins?
59 - 77 degrees F
What ester is responsible for banana aromas?
isoamyl acetate
What is the primary role of magnesium?
- found in chlorophyll and necessary for photosynthesis
How much rainfall per year does a vine need?
- 19 inches in cool regions
- 29 inches in warm regions
What causes chlorosis?
low iron levels in high pH soils
What are the 2 types of frost?
- advective
- radiative
What are the 2 types of buds?
- compound buds form in one growing season and open in the next
- prompt buds form and break in the same growing season
Dagger and root knot are types of what?
nematodes
What is the effect of too much nitrogen?
Excessive canopy growth
What is the main role of nitrogen?
Needed in proteins and chlorophyll for photosynthesis
What is the effect of under cropping?
- sugar deficit in grapes
- too many leaves create too much shade
What is the effect of too little potassium?
inhibits sugar accumulation in grapes
What is the effect of too little phosphorus?
poor root systems
What rootstocks are considered nematode resistant?
- Ramsey
- Dog Ridge
The uptake of what key nutrient is inhibited in low pH soils?
phosphorus
What does the Huglin Index take into account?
- mean and max temps
- day length at altitude
What is the effect of too little magnesium?
- poor yields
- poor ripening
What are the visual symptoms of Dead Arm?
- stunted shoot growth
- yellow leaves
What are common methods of must concentration?
- reverse osmosis
- vacuum extraction
- cryoextraction
During which development stage does chlorophyll begin to break down and anthocyanins synthesize?
Veraison
What is the primary role of potassium?
Regulates water flow in vines
What is the main symptom of phopmosis?
Canes turn white and become brittle