Viticulture and Vinification

Question 1

When does the annual life cycle of the vine begin?

Answer 1

Sometime around February when the average temperature rises above 50F (Northern Hemisphere). Vines awake from dormancy then.

Question 2

What and when is the first stage of the vine’s life cycle?

Answer 2

Budbreak. In March or April for the Northern Hemisphere.

Question 3

What is the main viticultural hazard during bud break?

Answer 3

Frost

Question 4

What is the second stage of the vine’s life cycle following bud break and when does this occur?

Answer 4

Flowering. 6-13 weeks after bud break depending on the climate.

Question 5

What happens during bud break?

Answer 5

Small shoots and leaves break through the buds left intact after winter pruning. The vine’s foliage developed through the early spring and small green clusters called embryo bunches form on the shoots by mid April.

Question 6

What happens during flowering?

Answer 6

The embryo bunches bloom into small flowers for about 10 days and the self-pollinating grape vine begins the process of fertilization.

Question 7

What is the next stage of the vine’s cycle following flowering?

Answer 7

Fruit set.

Question 8

What percentage of embryo’s successfully reach fruit set? What happens to the rest?

Answer 8

Around 30%. The rest “shatter” and fall from the cluster.

Question 9

What is the next step of the vine’s cycle following fruit set and what happens in between these two stages?

Answer 9

Veraison. Leading up to Veraison, the berries enlarge but remain hard, high in acidity, and low in sugar.

Question 10

When does veraison usually occur and what happens during this stage?

Answer 10

Usually in August. Sugars move from the leaf system to the grapes. As this happens the grapes soften and change color from green to red-black or yellow-green.

Question 11

During veraison what can happen in regards to cluster ripening?

Answer 11

The grapes on the cluster can ripen unevenly. Zinfandel is notorious for this.

Question 12

In addition to the grapes, what else ripens during veraison?

Answer 12

The canes on the vine also ripen, lignifying while accumulating carbohydrates to sustain the plant through the winter.

Question 13

When does the harvest occur?

Answer 13

Once the grapes have achieved the optimal balance between sugar and acid.

Question 14

When does harvest occur in the Northern Hemisphere?

Answer 14

Harvest begins as early as August and can last through the beginning of November. Some grapes destined for late harvest wine or ice wine production may stay on the vine longer.

Question 15

What happens to the vine after harvest?

Answer 15

The vine loses its leaves and enters a period of winter dormancy where fertilization can occur following harvest in the fall and pruning follows in the winter to prepare the vine for next year’s growth.

Question 16

New World winemakers have advanced the idea of complete physiological ripeness. What is this?

Answer 16

A concept of ripeness comprising not only must weight and pH, but also ripening of tannin and other phenolics, the condition of its pulp, and seed lignification- which often requires longer “hang time” for the grapes on the vine.

Question 17

What is the main hazard during flowering?

Answer 17

Damaging effects from the cold, frost, or wind.

Question 18

What does climate encompass?

Answer 18

temperature, rainfall, sunshine, wind, and other atmospheric elements, and remains relatively stable from year to year.

Question 19

What is the mean annual temperature that the vine prefers?

Answer 19

between 50-68 degrees, with an ideal of 57.

Question 20

What average summer temperature is required to successfully ripen red grapes? White?

Answer 20

70 for reds, 66 for whites.

Question 21

What is the purpose of the California Heat Summation Index?

Answer 21

To classify climates based on temperature and by so doing identify land where a particular set of grape varietals can flourish based on what region classification that land falls under in the index.

Question 22

What quantifiable unit is used to discern a vineyard’s region classification according to the California Heat Summation Index?

Answer 22

degree days

Question 23

How are degree days calculated?

Answer 23

By multiplying the days in each month of the growing season (defined as April 1 through October 31) by the mean number of degrees over 50F for that month. The month’s totals are then added together to give the heat summation.

Question 24

What is the minimum amount of sunlight in hours that a vine needs?

Answer 24

1300 hours

Question 25

Sunshine during the growing season increases or decreases the farther one moves away from the equator?

Answer 25

increases

Question 26

How much annual rainfall does a vine need to produce an adequate crop?

Answer 26

20-30 inches

Question 27

If the vine receives too little water, water stress can occur. What does this do to the vine?

Answer 27

Promotes smaller berry sizes and yields but may lead to the vine completely shutting down if stress is too severe.

Question 28

What does too much rain do to the vine? How bad is it for the vine?

Answer 28

Too much rain does not adversely affect the vine itself but will dilute the fruit quality and create a friendly environment for fungal diseases.

Question 29

What are the positives and negatives of wind?

Answer 29

Positives are that it keeps the vine dry and in some cases can prevent frost by mixing the warmer air above the vines with the colder air that may threaten the vines. It can be very negative if it is too severe wherein it can undermine flowering or denude the vines. Persistent wind in cool climates can be devastating as well when it provides a cool chill.