Vitis Species
Family: Vitaceae

Known to have been cultivated since the fourth century BC. in Syria and Egypt and since 2500 BC around the Aegean, the origins of the grape, Vitis vinifera, are uncertain. This species, sometimes called European grape, and its culti­vars are now grown in many parts of the world both for table grapes and for wine. A number of American species, including V. labrusca, are grown both commercially and in home gar-dens. the many hybrids between V. vinifera and V. labrusca are now grown mainly as wine grapes. V. labrusca is very important commer­cially as a rootstock as it appears resistant to the insect pest, Phylloxera, which can wipe out enormous areas of vines. In some countries, strict quarantine requirements which restrict the importation and movement of grape vines between states and wine-growing regions are in force to try to keep vines free of this disastrous pest.

Species

V. vinifera is a vigorous, deciduous vine which develops a twisted woody trunk, covered with hark which is shed in strips. It has long, flexible branches and coarsely toothed, lobed leaves. The small, greenish flowers are borne in drooping clusters and the pulpy oval fruits, usu­ally containing two to four small, hard seeds, have either white or dark skins, covered with a white, powdery substance known as the bloom. Grapes may be eaten fresh, as table grapes, or they may be dried and sold as raisins, sultanas and currants. Grapes may be used also in wine and spirit making. Regarding suitable cultivars of American and European grapes for the home garden, bear in mind that there are scores of them, differing in climatic requirements, and availability will vary from one region to another. It is, therefore, best to buy locally available cultivars, as then you will know that they are right for your climate. There is a choice of grapes for both wine making and dessert.

Cultivation

Grapes are long-lived plants if pro­vided with appropriate conditions. They toler­ate cold winters if they have long, hot sum­mers, with low rainfall. However, high humid­ity in summer can lead to bunch rot, berry splitting, downy and powdery mildew, and black spot. Late spring frosts can severely damage flowers and reduce crop potential.

Grapes prefer a humus-rich, sandy soil, though any soil, except a heavy, waterlogged clay, is suitable, if it is well drained. Over-feeding will lead to excessive growth and reduction of crops. Grapes should be pruned during winter dormancy and may be trained along one or two horizontal wires to cover a wall or trellis, or into a bush or standard, which gives fewer but better bunches. In each case the aim is to produce a sturdy framework of trunk and branches which gives rise to annual shoots or canes.

Cut these back in winter, leaving only a few buds to pro-duce fruiting wood called spurs. The shoots from the buds on the spurs or rods bear the grapes in the following summer. The main trunk and branches will be formed in the first two or three years. Cut back the newly planted bush to two or three buds and the following winter cut out the weaker shoots. Tie the strongest shoots to a post and tip prune back to the desired height, 20-50 cm (8-20 in) for a standard, or to the height of the horizontal wire or the lowest horizontal on a trellis. If neces­sary, repeat this type of pruning the next year until the required height is reached.

The two strongest shoots from this trunk should be trained along the horizontal wire or trellis in opposite directions and cut back; if a standard is required, three or four well-spaced canes should be pruned back to two or three buds on the trunk. The rest should be cut out.

Grapes are produced on shoots of the current year's wood, which comes from the canes of the pre­vious season's growth. Grapes do not ripen well after cutting so they should be left on the vine until they are ripe. Grapes may be attacked by mites, mealy bug and thrips. They are also very sensitive to spray drift from herbicides.

Climate

Zone 5 or 6.