Objectives
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Delineate why certain grape types are grown in certain regions
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Explain impact of sun, soil, rainfall and wind on grape quality
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Examine parts of the grape and which parts contribute to wine
taste
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List grape pests and diseases
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Understand the impact of phylloxera worldwide
Definitions
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Viticulture - study of grape growing
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Allelopathic effect - prevention of growth of competing plants by
secreting growth inhibitors into the soil
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Varietal - a wine based on the variety of grape used to make the
wine
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Heat degree days - way to determine if climate is suitable for
certain varietals
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Terroir - French word for "earth" or "soil"; used to generally
describe nuances imparted by soil and climatic factors in certain
wine-growing regions and includes localized climate, soil type,
drainage, wind direction, humidity and all other factors that make one
grape-growing location different from another
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Odium (powdery mildew) - fungal disease of grapes
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Botrytis cinerea - fungus called "noble rot;" can lead to high
quality wines
Viticulture
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Important because finished wine can be no better than the
starting grape
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Grapes are temperate in nature and require a winter dormant
period
Grape Types
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Grape varieties can be
divided into table (e.g., Thompson seedless) and wine (e.g., Merlot)
grapes
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5000 wine grape species but
200-300 are important
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Physical characteristics are
different for table & wine grapes
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European grapes are Vitis
vinifera and can grow many places
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Native American grapes
are cold tolerant and resistant to phylloxera
V. labrusca
grapes grow well in the Eastern US
Vitis rotundifolia
grow in the southeast US
§
Muscadine is the most
popular varietal
Native American grapes
typically used for rootstock are V. riparia (riverbank grape) and
V. rupestris (sand grape)
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French American hybrids
combine characteristics of V. vinifera & Vitis labrusca
Yield from typical vines
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1 gallon fills about 5 standard 750ml bottles
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Mature vinifera vines yield 8-12 lbs of grapes/vine
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Labrusca has slightly higher yields
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Need 10-12 lbs/gallon therefore 1 vine to make 1 gallon or ~5
standard bottles
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In America, typically plant ~600 vines/acre, which yields ~3000
bottle of wine
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One person can handle about 10 acres of vines
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In Europe, typically plant about 3000 vines/acre
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This high density creates a strong allelopathic effect
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3yrs for chemicals to clear once removed, 3yrs for 1st crop once
plant
Viticulture
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Various grape species have a wide range of tolerable growing
conditions
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Best wines come from grapes grown at the limits of their range
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"To produce great wine, the vine must suffer"
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One source of "suffering" is by planting as far north as the vine
will tolerate
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Vines need 22" rain/yr, cold Winter, hot Summer, dry Fall, and at
least 30" of well-drained, sandy, gravely soil
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Higher quality grapes come from old vines
Grape "Anatomy"
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Peel skin off red grape and save
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Color is in skin
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Center is sweet – it contains all the sugar
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Skin is tannic (astringent), bitter, sour & contains other fruit
flavors (like berry)
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Chew on the stem and see that it is VERY astringent
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Niagara – tough, slimy, hard to chew, has an after-taste
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Seeds are so tightly clustered in V. Labrusca, do not
separate until pressed
Suffering vines
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"To produce great wine, the vine must suffer"
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Flavors of the grape are in and adjacent to the skin
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the smaller the berry, the more intense the flavors
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Stressing the vines results
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low crop yields, higher fruit quality, more concentrated flavors
in final wine
Selection of appropriate grapes
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Soil type
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Climate
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Role of microclimate
Sun angle (sunny side or
shady side?), Slope (hill better than valleys), Wind, Nearby vegetation
and bodies of water (if you can see it, it impacts)
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What the French mean by terroir
Climate and soil factors
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Grapes need at least 22” of
rain/year
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Need spring and summer rain
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Need dry near and during
harvest
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Sugar is made in leaves and
translocated to grapes just before grapes are ripe
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Plant produces berries and
sugar only when it is >50F
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Leads to concept of degree
days - the # of days warmer than 50F
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Example: 20 days at 70 and
30 days at 80
= 1300 degree days 20(70-50)+30(80-50) =
1300
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1700-4000 degree days needed
for wine grapes
Degree Day Regions
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Regions placed into categories based on degree days
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Region I is very cool (<2500 degree days)
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Below this, you cannot grow grapes
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Region V is very warm (>4500 degree days)
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Includes Spain, Sicily, San Joaquin Valley
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High end, red grapes should be grown
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Wines tend to be "flabby"− high in alcohol, low in flavor &
crispness
Trellising
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Grapes in the wild naturally trellis in trees
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Some places in Italy still use this method
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Most use some sort of manufactured trellis
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Number of commercial trellising systems and choice depends on
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Sunshine, wind, humidity, grape variety
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Need to get the vines off the ground, away from pests, improved
ventilation, and exposure of the grapes to the sun
Pruning
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Pruning is done when plants are dormant
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Grapes are formed only on new canes
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Pruning
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removes non-productive canes
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keeps the plant under control
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prevents overproduction of grapes (overcropping)
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Cluster thinning (prevent overcropping)
Other grape pests
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Animals – birds, rodents, deer, etc.
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Molds and mildew – resveratrol is natural defense
Odium ( powdery mildew), Downy mildew,
Black rot, Botrytis cinerea
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Insects – Multicolored Asian Lady Beetle
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Various diseases
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Biggest pest is PHYLLOXERA
Impact of phylloxera
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Grape louse that is nearly microscopic
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Devastated much of European grape vineyards in late 1800s
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Style similarities in divergent parts of Europe are due to
vineyard workers moving from devastated areas to new areas
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Mechanical harvesting and increased traffic in vineyards spreads
the problem
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No good treatment other than using phylloxera tolerant rootstock
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