Fundamentals Unit Part 2 - Viticulture Flashcards
Name the main annual vineyard events.
Dormancy, Winter pruning, Bud Break, Flowering, Fruit Set, Leaf Pulling and Green Pruning, Veraison, Harvest, Fertilise and Hill Up, Leaf Fall and Trellis Adjustment
When does the vineyard cycle run from/to?
December to November (although exact dates may vary).
What is meant by dormancy? Why is it important to the the vine?
One the weather becomes colder(below 10C) the growing season has ended and the vine will go into dormancy. This allows the vine to store its carbohydrates for winter and recover for the new season. For some vines this is essential or it can deteriorate. eg Riesling.
Why is winter pruning carried out?
It prepares the vine for the next season. It determines the number and location of buds that will form shoots in the following season. It is important for canopy management and yield prediction and management.
What happens at bud break/budburst? What can impact this process?
At the start of spring( March) buds swell and open to grow into new shoots. The danger is severe cold/frost can damage or slow this process affecting yield. Warmth can accelerate the process. Earth used to hill up will be removed.
How is early shoot and leaf growth supported?
They use up stored carbohydrates and then photosynthesis. They need plenty of water and nutrients at this stage.
How long after bud break does flowering occur? What is the term for these?
It occurs 6-9 weeks after bud break,(May) weather permitting. They are known as inflorescences. Typically last 8-10 days.
What is fruit set?
Fruit set occurs after the self-pollination of the flowers. The flowers develop into small, hard, green grapes, high in acid and low in sugar.
What is coulure? Millerandage?
Coulure is the French term for when more flowers than normal fail to fertilise after fruit set. They fall off the vine.
Millerandage occurs when berries develop without seeds and remain small.
What effect do coulure and millerandage have?
They are normally caused by cold, cloudy and rainy weather and reduce yield. Merlot and Malbec are most vulnerable.
When are early-ripening varieties picked? Late-ripening?
Early - 8-10 weeks after fruit set;
Late - up to 18 weeks after fruit set
When/Why is leaf-pulling/summer pruning carried out?
In July. It is done to ensure the canopy remains open for sufficient sunlight and air circulation for the grapes. This mitigates disease pressure and humidity.
What is the purpose of Green Harvesting?
Green harvesting is a method of controlling yield and improving grape quality. It can be done after version but is not universally carried out.
What is Veraison and when does it occur?
Veraison, occurs around July, and is the point at which berries change colour from green and begin to ripen. Black varieties turn purple, white turn to translucent and golden.
What happens in the grape during ripening?
Acid levels fall and sugar level rises. Tannins mature flavour and colour intensifies
What influences the harvest date?
It can happen between Sept and Nov. depending on variety ripening curve and wine style eg VT or SGN As a general rule most grapes are picked 45 days after version.. It is also influenced by the number of sunshine hours, heat and the growing conditions. Climate change has impacted this as well.
How long on average does the growing season last?
Between 165 - 180 days in total.
What is hilling up and why is carried out?
It the process of building earth up around the trunk of the vine specifically to protect the graft union during winter from extreme weather and cold which might cause damage.
What happens to shoots after harvest?
They lignify and become woody canes known as 1 year wood.
What is phylloxera. What does it do to vitas vinifera?
It is an aphid which is indigenous to N. America. It came to Europe in 1860s. It attacks the vine roots and injects saliva into wounds. The vine is unable to heal itself so becomes infected by other fungi and bacteria and eventually will die. It devastated the vineyards of France.
What was the remedy for Phylloxera in France?
It was discovered that American rootstock are immune to this pest. Grafting of VV cutting/cane/bud onto an American rootstock solved the problem and is the current method.
What improvements resulted from Phylloxeras arrival?
- No more layering (mar cottage/provignage) brought order;
- Single grape variety planting in parcels to mange maturity and ripeness. Previously multiple varieties planted and fermented together at different stages of ripeness.
- Change to vineyard composition. ie varieties planted.
What is powdery mildew? How is it combatted?
It is also known as OIDIUM. It is a fungal disease which covers the green parts of the vine with thick white filaments. Sulphur spray is used to combat it.
How does OIDIUM affect the grapes?
If it attacks before flowering yield will be reduced. If grape clusters are infected they will not achieve full pigment development nor grow fully and develop off flavours
What is Downy Mildew? How is it combatted?
It is also known as PERONOSPERA. It germinates in warm humid weather and attacks the shoots and leaves with what look like “oil spots” then white cotton filaments. The “Bordeaux Mix” of copper-sulfate is is used to combat it.
How does PERONOSPERA affect the grapes?
It causes the vine to lose its leaves which can reduce/stop photosynthesis, which can delay or stop ripening altogether.
What has been a more recent threat to the vineyards?
Asian fruit fly (Drosophila Suzuki).