Note 109 — Chapter III · THE VITICULTURE OF NEW YORK

Anthracnose (Sphaceloma ampelinum De By.).—This disease attacks any of the tender portions of the growing vine. When the leaves are affected dark spots are first formed on their surface. As the disease advances these spots enlarge, and irregular cracks are often formed through the dead tissue. Frequently many of these small cracks run together, forming a long irregular slit through the leaf. Similar marks are formed on the tender shoots, though they are not so noticeable. When the fruit is attacked the disease is sometimes called bird’s-eye rot. Circular spots are formed on the surface of the berry. The spots may be of different colors and usually have a dark border; as the spots enlarge and eat in, a seed is often exposed in the center. In rotting the tissue becomes hard and wrinkled. Sometimes the disease girdles the stem of a fruit cluster, cutting off the supply of sap from the grapes beyond the diseased line and causing them to shrivel and die.

Anthracnose does not spread as rapidly as some other vineyard diseases, neither does it yield as readily to treatment. When a vineyard is badly infested with anthracnose, it requires prompt attention and a careful treatment to control the disease. It is not satisfactorily controlled by bordeaux mixture alone. It is suggested that in addition to such treatment with this mixture as is given for black-rot the plan be followed which is advocated by certain European authorities, of applying a warm saturated solution of copperas (iron sulphate) in spring when the buds are swelling but before they begin to open. One per ct. or more of sulphuric acid may be added to the solution before it is applied. This solution must be handled with care as it is very caustic. It is applied with swabs or if the acid is not used it may be sprayed. It is essential that the work be done thoroughly, covering all the surface of the canes.