What are the 5 most important things a vine needs to survive?
- Carbon dioxide
Finish this equation:
Sunlight + CO2 + Water = ____ and ____
Glucose and Oxygen
Vines use ___ and ___ to fuel its growth and ripen its grapes.
Glucose and nutrients from the soil
Oxygen is one of the byproducts of photosynthesis, but vines don’t use oxygen.
What does the vine do with the oxygen it creates during photosynthesis?
The vines release it through their leaves.
What is the defining factor that determines which grape varieties can grow where?
The amount of heat an area gets during its growing season.
Something to keep in mind: continentality + a region’s proximity to bodies of water are tied into this because they help influence the region’s total amount of heat during the growing season.
What 7 natural factors affect/influence temperature and heat in a vineyard?
- Ocean Currents
- Soil structure
- Slopes and aspect
- Diurnal range
What 3 factors affect/influence sunlight in a vineyard?
- Bodies of water
What are the optimal latitudes for growing vines around the world?
Between the 30th and 50th latitudes north and south of the Equator.
Put another way, between latitudes 30 and 50 degrees in the northern and southern hemispheres.
Why isn’t it possible to cultivate grape vines close to the Equator?
Because areas close to the Equator have annual average temperatures that are far too high which do not allow the vine to go dormant. And if a vine is unable to go dormant, it’ll produce less-than-optimal fruit and tire out in only 15-20 years.
Fun Fact: there is one place in Northern Brazil, Vale de São Francisco, that is capable of two harvests per year.
How does altitude affect temperature?
As altitude increases, temperature decreases.
Altitude is what allows some regions to exist closer to the Equator, e.g. Cafayate, Argentina which sits ~3,000m above sea level.
What is the effect of the Gulf Stream on Europe?
The Gulf Stream adds a warming effect to the climates of northern and western Europe.
The Gulf Stream originates near the tip of Florida and crosses the Atlantic Ocean.
What is the cold ocean current that affects South Africa?
Name the cold ocean current that affects Chile.
How can fog be beneficial to vineyards?
It can have a cooling effect on vineyards which would otherwise have difficulty growing premium grapes (the vineyards would get hot and stay hot).
How can soil affect a vineyard’s temperature?
Rocky, slatey soils - stony or dark in color - absorb heat during the day, and release it overnight.
- Galets roulés in Châteauneuf-du-Pape
- Blue slate in the Mosel
- Llicorella soil in Priorat
Which way do vineyards face in each hemisphere to ensure optimal sun exposure?
Vineyards in both hemispheres will face the Equator for optimal sun exposure.
Northern hemisphere vineyards will face south.
Southern hemisphere vineyards will face north.
What is a diurnal shift?
A diurnal shift is the change in temperature from daytime to nighttime.
The larger the diurnal shift (lower lows, higher highs) the better it is for the vine; warm daytime temps help develop sugar and phenolic ripeness whereas cool nighttime temps help preserve acidity and freshness.
What are two things that can reduce diurnal range?
- A vineyard’s proximity to a body of water
- Cloud cover
Besides decreasing diurnal range, how else does cloud cover affect a vineyard/vines?
- Slow flowering and fruit set because the vine isn’t getting enough sunlight to photosynthesize, which will ultimately produce a smaller crop;
- Heavy clouds can stop grapes from fully ripening.
What does continentality mean?
Continentality is the difference of temperature between the coldest month and the hottest month in a region.
Regions with high continentality have big temperature differences between their coldest winter months and their hottest summer months.
Regions with low continentality have less of a difference in temperatures throughout the year.
What effects do bodies of water (oceans, lakes, rivers) have on climate?
Bodies of water help moderate temperatures, reducing continentality; meaning, temperatures will hit neither extreme lows nor severe highs.
Vineyards in close proximity to bodies of water have diminished diurnal range as bodies of water emit stored warmth at night (and during the beginning of winter) and supply cool daytime breezes.
Describe lake effect.
As large bodies of water take a long time to warm up and cool down, ‘lake effect’ has a moderating aspect on climate.
During the autumn, a lake that has warmed up over the summer releases its accumulated warmth to the surrounding land thereby extending the growing season for grapes and keeping away early frosts.
During the spring and early summer, the lake is still cold from winter. As the land around a lake heats up, warm air rises from the earth which sucks in the cool air coming off the lake, creating on-shore breezes.
At what temperature can vines be damaged or killed by a deep winter freeze?
The part of the vine that’s most susceptible to winter freezes is the ___.
Graft (if the vine has been grafted)
What does ‘earthing up’ mean?
‘Earthing up’ is when a viticulturist mounds up additional soil around the base of the vine’s trunk as an insulation layer to help retain warmth over winter.
This is done to young vines in particular to protect against deep winter freezes, especially new grafts.
Describe what spring frost is.
What kind of damage can it do?
When cold air (below 0ºC) freezes water vapor hovering at ground level or around the vine.
Frost can kill new shoots and buds that have just burst, impacting yields.
What are the 4 important protections a viticulturist can take against frost?
- Heaters and smudge pots which create a blanket of warmth to keep the vineyard from freezing;
- Fans, wind machines, or helicopters to circulate warm air above the ground with the cold air that settled around the vines;
- Sprinklers, which spray water onto a vineyard so that a thin layer of ice forms on the vine which helps insulate it;
- Conscientious vineyard design to avoid depressions; can also high-train vines.
Why do rivers mitigate frost damage?
Because river currents keep air moving - instead of settling - in vineyards.
What can cold springtime temperatures lead to?
- Delayed budburst –> shortens growing season
- Disrupted flowering/fruit set –> lower yield
What can sustained, extremely high summertime temperatures lead to?
- Slow or stalled vine activity –> vine can shut down
- Death of the vine
What 2 climate features are most influential on grapevines?
What is the difference between climate and weather?
Climate is what you expect; weather is what you get.
- Climate is a region’s expected, annual average of temperature, sunlight, warmth and rainfall over time;
- Weather is what happens day-to-day and what you see outside your window.
What are the months defined as the “growing season” in the Northern and Southern Hemispheres?
Northern: April - October
Southern: October - April
Define cool climate.
A region with a cool climate will have an average growing season temperature of 16.5°C (62ºF) and below.
Define moderate climate.
A region with a moderate climate will have an average growing season temperature of 16.5°C - 18.5°C (62º - 65ºF).
Define warm climate.
A region with a warm climate will have an average growing season temperature of 18.5°C - 21°C (65º - 70ºF).
Define hot climate.
A region with a hot climate will have an average growing season temperature 21°C (70ºF) and above.
Describe Maritime climate.
Low continentality areas that are influenced by large bodies of water and have warm summers and mild winters with rain falling year-round.
Bordeaux and Rías Baixas are examples of Maritime climates.
Describe Mediterranean climate.
Low continentality areas that have very warm, dry summers and cool, rainy winters.
They tend to produce fuller, riper wines.
Southern Rhône and McLaren Vale are examples of Mediterranean climates.
Describe Continental climate.
High continentality with climate extremes: warm and/or dry summers with cold winters.
They tend to be interior regions.
Champagne has a cool Continental climate; Ribera del Duero has a warm Continental climate.
What encourages Noble Rot (Botrytis)?
When early morning mists or fog from nearby bodies of water create humid land conditions which are then followed by warm, dry, and sunny afternoons.
The humidity allows the Botrytis spores to attack the grapes; the sun-filled afternoons allow the spores to germinate.
Sauternes and Tokaji are examples where this phenomenon happens.
What is the rain shadow effect?
As weather systems move from west to east, foul weather is stopped by or trapped in mountains thereby leaving the eastern side of mountains with brilliant sunshine and nice weather. The western side gets all the rain and clouds.
The Vosges, Cascades, and Andes Mountains are all examples of mountain ranges that create rain shadows.
Because rain shadows provide warm, sunny weather for the leeward side of mountains, what does that allow vignerons in rain shadows to do?
Vignerons can plant vineyards at higher altitudes on the leeward side to help the vines find cool nights, down drafts, and drainage.
Salta, Argentina is an example of an appellation planted at higher altitude on the eastern slopes of mountain ranges.
What happens to a vine when it suffers from drought conditions?
A vine will shut down if it doesn’t have enough water to produce photosynthesis.
- leaves will stop all work
- sugars won’t be produced
- grapes won’t ripen properly
What is the difference between altitude and aspect?
Altitude is height above sea level, e.g. the Uco Valley in Mendoza, Argentina is 3000-4900ft (900-1500m) above sea level (a.s.l.)
Aspect indicates the direction which a slope faces, e.g. top sites in Burgundy have a southeasterly aspect which provides them more gentle morning sun and protects them from hot afternoon sun.
Why is rain at harvest not a good thing?
Rain at harvest can result in:
- Dilution of flavors in grapes
- Dilution of sugars in grapes
- Create rot
This is why winemakers will have to decide to pick either before a big rain or wait several days after the rain for the vines to metabolize the rainwater.
What is the damage that hail can do to a vineyard?
- Perforate leaves rendering them unable to photosynthesize;
- Damage bud wood, creating open wounds which invite bacteria;
- Knock clusters or grapes off the vine, decreasing yields.