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Define Macro-, meso-, and micro- climate
- Macroclimate: regional,up to hundreds of km, e.g., Bordeaux
- Mesoclimate: a vineyard to a sub-region, up to a few km, e.g., Pomerol
- Microclimate: an individual vine
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Name some factors that affect the microclimate
- Relationship with its neighboring vines
- row width
- planting distances
- trellising and training type
- height of trellis
- methods of canopy management
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Grapevines respond to differences in climate more than an other fruit crop. T or F?
True
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The sugar level in grapes at harvest is directly related to site quality. T or F?
True. In many instances the financial value of the grapes will depend entirely on the sugar level at harvest.
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What is the effect on wine of sugar and acid levels?
- Sugar: if low, thin and unripe; if high, alcoholic, warm and unbalanced
- Acid: if low, flabby and short-lived; if high, acidic and aggressive
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Name the 3 most important factors of site selection in growing grapes
- Latitude (location)
- Altitude
- Aspect
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Name 15 fixed factors of site selection in growing grapes
- Length of the growing season
- Number of sunshine hours
- Diurnal temperature range (affects speed of ripening and acid reduction)
- Site's relationship to prevailing winds
- Proximity of large bodies of water
- Rainfall
- Humidity and the evapotranspiration (ET) rate
- Type and depth of soil
- Management of the vineyard floor (cultivated, bare earth, or grassed down)
- Layout of the vineyard (direction of rows)
- Trellising and training system
- Choice of rootstock
- Type and clone of grape variety
- Cropping level
- Wine type and quality level to be produced
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Name 3 variable factors of site selection in growing grapes
- Weather (most important)
- Pest & disease control
- Canopy management
- Irrigation regime
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Name 4 methods to measure the macroclimate
- Heat Summation (aka Degree Days, Winkler Scale, Regions I-V, Heat Units): Maynard A. Amerine and Albert J. Winkler, UC Davis, 1944
- Latitude Temperature Index (LTI): David Jackson and Danny Schuster, New Zealand, 1994
- MTWM - MTCM: difference between mean temperatures of warmest and coldest months;
- MTWM alone: Richard Smart and Peter Dry, Australia, 1980; good corrleation to degree days for wamer sites
- (10 year average of number of) days over 30°C: good for cooler regions
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Name the issues associated with the Heat Summation, LTI, and MTWM-MTCM methods
- Heat Summation: OK for California but not appropriate for cooler, less continental regions
- LTI: factors in latitude (length of the day); appropriate for cooler, less continental, more maritime regions
- MTWM - MTCM: factors in continentality of the site (length of growing season impacted by proximity to water bodies)
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What is the theory behind the Winkler Scale?
No shoot growth occurs below 50°F
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What is a degree day?
- Average daily temperature above 50°F
- Example calculation: (81°F + 57°F)/2 - 50°F = 19 degree days
- Heat Summation scale is the sum of all degree days between April 1 and October 31 (7 months = 213 days)
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What is the daily average degree days per climate region?
- Climate Region I: up to 11.7
- Climate Region II: from 11.7 to 14
- Climate Region III: from 14 to 16.4
- Climate Region IV: 16.4 to 18.8
- Climate Region V: more than 18.8
- Note: each region adds about 2.3°F to next cooler region
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Define the Winkler Scale and what grapes grow best in each region
- Climate Region I: up to 2,500 degree days; CS, CH, PN, Riesling, SB
- Climate Region II: from 2,500 to 3,000 degree days; same varieties as Region I plus merlot
- Climate Region III: from 3,000 to 3,500 degree days; Carignan, Ruby Cabernet, SB, Semillon, Zinfandel
- Climate Region IV: 3,500 to 4,000 degree days; Barbera, Ruby Cabernet, Emerald Riesling, port-style wine grapes
- Climate Region V: more than 4,000 degree days; Souzao, Tinta madera and Verdelho
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Define the Winkler Scale and name example areas for each region
- Climate Region I: up to 2,500 degree days; Champagne, Côte d'Or, Rhine
- Climate Region II: from 2,500 to 3,000 degree days; Bordeaux
- Climate Region III: from 3,000 to 3,500 degree days; Rhone
- Climate Region IV: 3,500 to 4,000 degree days; Southern Spain
- Climate Region V: more than 4,000 degree days; North Africa
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Name 2 ways to measure the length of the growing season
- Number of days between the last spring frost and the first winter frost (e.g., at least 180 frost-free days needed to ripen grapes)
- Number of days between start of flowering and start of harvest (e.g., Bordeaux usually 110, Central Otago up to 145)
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Best sites are those with what macroclimate measurements?
- Growing season of 180+ frost-free days
- Summer rainfall around 500 mm (19.7 in)
- LTI of 200+
- Degree Days of 1000+
- Sheltered from cooling winds
- Slope towards the sun
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Name 3 negative effects of global warming (e.g., 2°C rise in mean annual temperature)
- Need to switch varieties
- Need to learn about acidification and alcohol reduction techniques
- Change in the spectrum of pests and diseases
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What other factors might account for higher sugars attributed to global warming?
- Improved plant material (clones)
- Better canopy management
- Much better (chemical and viticultural) Botrytis control which allows for a longer ripening period
- Temperature control
- More alcohol-productive yeast strains
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Name an insect that has found its way to Europe, once considered too cool for it
- Multicolored Asian Lady Beetle (aka Harlequin Ladybird Harmonia axyridis)
- Exudes "reflex blood" from its legs which has a fould odor and taste (taints grapes and wine made from them)
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Name the world's coolest winegrowing region by far
U.K.; Cropping levels, at around 50-60 hl/ha, are lower than those in vineyards in Champagne
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Name 3 varieties for cool climates
- Muller-Thurgau
- Reichensteiner
- Seyval Blanc
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Has global warming changed the timing of bud-burst, flowering, veraison, or harvest?
No
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As you rise above sea-level, how does the annual mean temperature change?
- Temperature falls by around 0.5-0.6°C per 100 m rise (1.8°F per 109 yards)
- Sites also become more exposed to prevailing winds
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What is the effect of altitude on site selection?
- The higher the altitude, the shorter the growing season and ripening will occur later.
- This increases the dangers of frosts and disease.
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At what altitude are the most suitable sites in cooler and warmer regions?
- Cooler: below 300 m
- Warmer: up to 1000 m
- Hot: 1000+ m
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At what altitude is the highest vineyard in the world?
- Bodega Colome vineyards sit between 2300 and 3111 meters above sea level
- Located in Argentina, in the Upper Calchaqui Valleys in Salta, latitude 26°S
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What aspects are preferred?
Sites that slope towards the sun (to the south in the northern hemisphere, to the north in the southern hemisphere)
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What aspect catches the morning sun? What is the effect of this?
- SSE or SE in the northern hemisphere
- Site warms up more quickly after night cooling; may also be more sheltered from prevailing winds
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Sites with what aspect stays warmer into the evening?
- SSW or SW in the northern hemisphere (slopes that face east are favored over those that face west in the southern hemisphere)
- Dark or stone rich soils benefit from this but in many regions the cooling prevailing wind comes from this direction.
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What is insolation?
Incoming solar radiation
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When is incoming solar radiation the greatest?
- Insolation is greater the more the site is angled to the sun (up to a slope of about 40°)
- The effect is more significant at the end of the growing season
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Define "thermal zone"
- Slopes are warmer because air (as it is cooled by the land) travels down the slope to be replaced by warmer air from above.
- Example slopes with thermal zones are Corton hill in ALoxe-Corton and Kaiserstuhl in Baden.
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Name 3 advantages growing grapes on slopes have over flat sites
- Aspect
- Thermal zone (warmer)
- Thinner topsoil (less vigorous)
- Better drainage (dry out and warm up better)
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Does water or land store heat more effectively?
Water
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How are air temperatures equalized between land and water?
Warm air on the land rises and is replaced by cool air from the water.
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What is the Gulf Stream?
- A powerful, warm, and swift Atlantic ocean current, about 100 km wide X 1 km deep.
- Ocean currents are mainly caused by wind that forces the water to move in the same direction.
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How much does the Gulf Stream warm the land it touches?
About 9°C (16.2°F) above that for the latitude
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Are regions with small or large diurnal temperature swings preferred for grape growing?
- Small, in (cooler) old world, since they heat up more quickly in the day, thus advancing maturity.
- Large, in (warmer) new world, since cool nights aids in the retention of acids.
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