Pest and Diseases of Grapes

Date: Saturday February 28, 2009
Posted in: Home & Garden

The strong-growing varieties can be grown as cordons if the site is warm and the soil good. The rows have to be 6 feet apart and the cordons 10 feet apart in the rows. The cordons are trained horizontally and thus stakes and wiring must be provided. Under this system a stake with a minimum diameter of 3 inches, and preferably chestnut, should, when 2 feet of its base has been thoroughly treated with Cuprinol, be driven into the ground securely so that the top is 2 feet 3 inches above soil level.

In the spring choose the stoutest and strongest growth and tie this perpendicularly to a stake. Cut out all other growths and concentrate on this one. Do not carry out any summer pruning, just let this strong rod develop naturally. Next January cut this rod back to within 3 buds of its base. When the 3 buds grow out, keep them, tying them to stakes or bamboos so as to form a goblet shape. Do not do any summer pruning.

Once again in January cut back these 3 canes to within two buds of their base. Thus you will see that you are now producing your goblet-shaped bush with 6 branches. Each one of these 6 branches may carry six or seven bunches of grapes and the following January again they will be cut back to within two buds.

Red Spiders can be detected by examining the back of the leaf with a magnifying glass. Red Spider is a bad name. Yellow Mite would be better.

Powdery Mildew causes white patches to appear on the leaves and then the fruit, then the young shoots. Individual grapes that are attacked will either fall or go rotten. Vines that are mulched are seldom attacked with mildew, and when the young laterals are properly spaced out, so that they are not overcrowded, this disease seldom appears. Dusting the plants with a fine sulphur dust largely cures the trouble when seen.

When growing a vine against a wall the pruning may be similar. The rod instead of being taken along a lower wire can be trained, with a main rod growing upwards and with side permanent rods trained out at right angles. Thus a series of horizontal cordons are formed and the laterals they produce are pruned back hard each January. These are tied to wires stretched tightly in between the main wires.

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