Grape is the juicy berry from a plant called the grapevine. Grapes grow in clusters. They have smooth skins with colors ranging from green to yellow, pink, crimson, dark blue, or black. The berries may grow as small as peas or as large as small plums. Most, however, measure from 1/2 to 1 inch (1.3 to 2.5 centimeters) long.
Growers harvest millions of tons of grapes each year. Manufacturers use most of the annual grape crop to make wine. Much of the crop is sold as table grapes, which people eat fresh. The rest is used for drying into raisins, in making juice or jelly, and in canning. Grapes have a high sugar content, which makes them a good source of energy.
The top five grape-producing countries account for about half of the world’s grape production. They are China, France, Italy, Spain, and the United States
Fossils of grape leaves and seeds indicate that human beings have eaten grapes since prehistoric times. Egyptian tomb paintings that date back to 2440 B.C. depict the cultivation of grapes.
Kinds of grapes
The European grape ranks as the most important grape species (kind). Two other major species come from North America.
European grapes
account for about 95 percent of all grapes grown worldwide. Growers classify most European varieties as wine, table, or raisin grapes. Some varieties are classified in more than one of these groups.
Mature wine grapes contain an appropriate balance of natural fruit acids, sugars, and other compounds that provide aroma or flavor. Manufacturers use these grapes to produce a variety of wines. Table wines rank as the most common group. Other groups include sparkling wines, which contain bubbles of carbon dioxide gas, and fortified wines, which have extra alcohol added to them. Wine grapes also are used to make brandy, another alcoholic beverage. Leading wine grape varieties include the Airen, Cabernet Sauvignon, Carignan, Chardonnay, Colombard, Grenache, Merlot, and Trebbiano.
Table grapes should have a tasty, firm texture and a brilliant color. Most consumers prefer seedless types. The chief table grape varieties are the Thompson Seedless, also known as the Sultana, and the Red Globe. Other important types include the Flame Seedless, Red Crimson, and Ruby Seedless.
Raisin grapes usually have no seeds, and they develop a soft texture when dried. The most popular variety, the Thompson Seedless, produces raisins ranging in color from green to golden to dark brown, depending on the drying method. Other varieties include the Black Corinth and the Muscat of Alexandria.
North American grapes
consist of two main species: (1) fox grapes and (2) muscadine grapes. People may eat them fresh or as jelly or wine. A third class of North American grapes includes the many hybrids bred from other grape species. Grape breeders have developed hybrids from crosses between different North American species or between European and North American species. Most hybrids are eaten fresh or are used for wine.
Growers cultivate fox grapes chiefly in northeastern North America. The Concord ranks as the most important variety. It has purple berries. Much North American grape juice and grape jelly comes from Concord grapes. Other fox grapes include the Catawba, Delaware, and Niagara.
Muscadine grapes grow throughout the southeastern United States. Their natural resistance to insects, disease, and heat stress makes them well adapted to this area. The berries grow in small clusters and fall off singly as they ripen. Popular muscadine varieties include the Carlos and the Noble.
Growing grapes
European grapevines grow best in regions that have long, dry, warm to hot summers. In such areas, grapes tend to mature early and remain free from disease. European grapevines cannot stand winter temperatures less than 5 °F (–15 °C) without protection. North American grapevines can tolerate lower temperatures and more humid summers.
Planting and cultivating.
Growers usually reproduce grapevines by means of cuttings—that is, sections of canes (stems) that are cut in winter. The cuttings measure 12 to 18 inches (30 to 46 centimeters) long. They are buried in moist sand until early spring. At that time, workers plant the cuttings in nurseries, leaving one bud aboveground. The cuttings then grow into small grapevines called rootlings. During the following spring, workers dig them up and plant them in position in the vineyard.
Grapevines generally need to grow on such supporting structures as trellises. Farmers construct most trellises from posts and wires and usually arrange them in rows. They then train the vines to grow on the trellises. Every winter, workers prune the vines to regulate the number of buds, and thus the weight of fruit, produced on each vine. They remove approximately 90 percent of the previous season’s growth at pruning. Grapevines usually start to bear fruit in their third year in the vineyard. They can produce a full crop after 5 or 6 years. With proper care, a vine may bear from 15 to 80 pounds (7 to 36 kilograms) of grapes annually for many years.
Harvesting.
The buds of many grape varieties bloom in late spring. Grapevines produce clusters of small flowers, which develop into the berries. Harvesting of berries often takes place from summer to early fall. To harvest table grapes, workers carefully cut each cluster by its main stem and remove any damaged berries. For wine grapes and raisin grapes, harvesting may occur either by hand or by machine. Workers pack table grapes in the vineyard or in specially equipped buildings located nearby. They take wine grapes directly to a winery for crushing. Raisin grapes must be dried. In some regions, farmers place raisin grape clusters on sheets of heavy paper between the vine rows. They then leave the berries to dry in the sun. In other areas, drying takes place on shaded racks or on the vine itself.
Packing and shipping.
Workers pack table grapes in wide, shallow boxes that are padded to prevent the fruit from being bruised. The grapes are then precooled to about 40 °F (4 °C) and treated with sulfur dioxide gas to retard decay. Workers put the boxes into refrigerated trucks or railroad cars for shipment to market.
Diseases and pests.
Grapevines can suffer from such fungal diseases as powdery mildew and black rot and from bacterial and viral diseases. These diseases may attack different parts of the vine, including the berries. Growers control harmful fungi with a combination of practices, such as the use of chemical dusts and sprays. Bacterial and viral diseases can be avoided by planting certified disease-free varieties.
Major pests of grape crops include insects called grape phylloxera and roundworms called nematodes. Both can destroy the roots of European grapevines. Farmers may control these pests by grafting. In this process, they attach a cutting from a European grapevine to the rootstock (root or root and stem) of a pest-resistant North American grapevine.
See also Grafting ; Phylloxera ; Pruning ; Raisin ; Wine .
