The different forms of rot of the grape, especially in the South, such as black rot, brown rot, and ripe or bitter rot, are controlled by a similar system of spraying. The usual plan has been to begin the spraying after the diseases begin to appear. But recent experience favors the first spraying with the double strength Bordeaux mixture before growth starts in the spring and continue with the ordinary strength at intervals of two weeks until the fruit is two thirds grown. During the seasons when the black rot is specially common the later applications, to prevent coloring of the fruit, are made with ammoniacal carbonate of copper, which is made by dissolving one ounce of carbonate of copper in one pint of strong ammonia. When used it is diluted with from eight to ten gallons of water. This solution is used in place of the Bordeaux mixture on ornamental plants and in all cases where the standard mixture is liable to color fruits. The powdery mildew of the grape is a surface-feeding fungus and easier to manage than the rots. If it occurs in connection with the rots the ordinary spraying will destroy it. But at the North and in the West it often occurs as a single disease. In such cases the flowers of sulphur is often used in a dry state by dusting, or by spraying with sulphured water. If it occurs when the fruit is well advanced the carbonate of copper dissolved in ammonia is used.
As with the raspberry the anthracnose or bird's-eye rot of the grape is the most difficult disease to treat successfully. This is an old disease of the grape in the wine-producing districts of Europe. The European treatment has proven successful where tried in this country, but it must be methodically practised. In the dormant season the canes, vineyard-stakes, and wires are washed with a solution of water, iron sulphate, and sulphuric acid. The formula is one hundred parts of water, with as much iron sulphate as the water will dissolve. To this mixture one part of sulphuric acid is added. It is applied with swabs or brushes with quite long handles and it blackens everything it touches. It needs care, as it is caustic if it gets on hands or clothes. In the growing season the usual sprayings for the rots are also favorable for keeping down the ravages of the anthracnose.
The strawberry-leaf blight and mildew can be controlled by spraying with Bordeaux mixture as soon as growth starts in the spring and repeating it when the blossoms are about to expand. If the diseases are well established it is best to mow and lightly burn over the plantation after picking-time. But some mow and rake the litter from the ground before burning, as they believe the burning an injury to the plants, which it is in a dry time. But when the ground is moist we have noted no injury, even where a light straw covering was given to assist in burning.
The anthracnose of the raspberry is most easily attacked by spraying with very strong solution of copper sulphate before the leaves expand in spring, followed with the Bordeaux mixture every two weeks until midsummer.
But the writer's long experience favors the destruction of plantations attacked by anthracnose or red rust and to plant on fresh ground, if possible, where the plants are sheltered from the direct sweep of the westerly winds.