VITICULTURE

INTRODUCTION In this module, we will introduce the basic terms and concepts of viticulture — the science of fine wine grape growing. We will also cover the annual life cycle of the vine and exactly what a grape vine needs to thrive and survive during the growing season. Remember, the growing season is in opposite months in the Southern Hemisphere.

MODULE OBJECTIVES In this module you will learn: The basic terms and concepts of viticulture — the science of grape growing The anatomy of a wine grape and grape vine An introduction to the annual life cycle of the vine

WHAT IS VITICULTURE Viticulture is the branch of agriculture that involves the science of grape growing. It has been said that wine is the second oldest beverage after water; and grapes have been cultivated for the purpose of winemaking for thousands of years. It is only within the last century that grape growing has become elevated to its current status that is a combination of science and art.

ANATOMY OF A WINE GRAPE Stem: usually removed before the grapes are pressed or crushed. Sometimes stems are included in red wine fermentation to increase the amount of tannins in the finished wine. Skin: skins of red grapes provide color and tannin. White wines are made without skin contact. The outside of mature grape may contain up to 100,000 yeast cells which may be used for fermentation.

ANATOMY OF A WINE GRAPE Pulp: produces the juice, or must, as it is called during fermentation. The pulp provides water, fruit flavors, and sugar required for fermentation. Pips: or seeds are not crushed during the wine- making process as they contain bitter oils which would spoil the wine.

ANATOMY OF A GRAPE VINE Tendril Bunch Leaf Node Cane/Arm Trunk Soil line Roots

ANNUAL LIFE CYCLE OF THE VINE Dormancy Bud-Break Foliage Development Flowering Fruit Set Ripening of Fruit Harvest Late Harvest

DORMANCY: WINTER While the vines are dormant during winter, most of the work in the vineyard involves pruning or cutting back the canes leaving a few buds for the next season’s growth. “Weeping” is the first sign of the new growing season, and takes place in: February for the Northern Hemisphere August for the Southern Hemisphere At that time, the soil temperature rises to 50°, warm enough for the vine roots to begin to collect water. Then sap rises up through the vine and oozes from the cane ends which have been pruned during the winter. Pruning for spring growth continues at this time but the vines are very vulnerable to early spring frosts which can freeze and kill the new buds.

BUD-BREAK-SPRING In spring, bud-break takes place some 20–30 days after the vine starts to weep. The exact date varies with different grape varieties. March–April in the Northern Hemisphere September–October in the Southern Hemisphere During bud-break the first new growth of the season appears. At this time spring pruning continues and the vines are secured to training wires. Aerating the soil is another important vineyard activity and the threat of frost continues.

FOLIAGE DEVELOPMENT: SPRING Following bud-break, small shoots emerge from the vines and tiny green embryo clusters form. These small clusters will eventually become grapes. This foliage development happens in spring: April–May in the Northern Hemisphere October–November in the Southern Hemisphere At this time the vines are sprayed for pests if necessary, and the vineyards are fertilized.

FLOWERING: LATE SPRING/ EARLY SUMMER Flowering of the vines takes place late spring/early summer, approximately eight weeks after bud-break: May–June in the Northern Hemisphere November–October in the Southern Hemisphere The weather must be dry and frost-free, and temperature is critical: 68°– 77 ° is optimum.

FRUIT SET: SUMMER Fruit set takes place in summer: June–July in the Northern Hemisphere December–January in the Southern Hemisphere After flowering the fruit evolves rapidly, with the exact number of grapes per bunch varying with the specific grape variety. Spraying, summer pruning, and weeding all continue in the vineyard at this time.

RIPENING OF FRUIT: SUMMER The fruit begins to ripen during verasion, the stage when the grape skins change color and the flavors begin to develop. This happens later in summer: August in the Northern Hemisphere February in the Southern Hemisphere During this time the sugar content in the grapes increases. Also, the tart malic acid in them decreases while the more important tartaric acid increases. The seeds of the grapes also begin to mature as well as the tannins. In the vineyard spraying and weeding continues. Leaf pulling and canopy management (trimming the leaves of the vine to make sure the grapes receive enough sunlight to fully ripen) also takes place.

HARVEST: LATE SUMMER THROUGH MID FALL Harvest takes place late summer through mid-fall: August–October in the Northern Hemisphere February–April in the Southern Hemisphere It varies with different locations, specific grape varieties, and wine styles: Generally, whites grapes are harvested before red grapes. Harvest for sparkling wine grapes takes place before still wine grapes. Grapes used for late harvest, dessert wines are harvested last. Harvesting is done either by hand or machine. Most fine wine in the U.S. is made from hand-harvested grapes.

LATE HARVEST: LATE FALL THROUGH MID WINTER Late-harvesting grapes for dessert wines takes place: November - January in the Northern Hemisphere May - July in the Southern Hemisphere Some dessert wines are made from grapes affected with botrytis. Botrytis is a mold, that forms in some growing regions under certain conditions. While disastrous when it develops on red wine grapes (called gray rot), botrytis is responsible for many of the world’s greatest dessert wines. November in the Northern Hemisphere May in the Southern Hemisphere With the first hard frost, grapes for ice wine are harvested. With the arrival of winter, the growing season begins again with dormant pruning.

REVIEW You should now have a good understanding of: The basic terms and concepts of viticulture The anatomy of a wine grape and grape vine The basic annual life cycle of a vine