37 



FUNGOUS DISEASES OF THE GRAPE. 



Anthracnose. 

 (Sphaceloma Ampelinum, De Bary.) 



Description. — This is a fungus which attacks all parts of the Grape 

 Vine, but most commonly the berries. The name, anthracnose, means 

 coal-disease, the disease is so-called from the dark colouration of the 

 affected parts. 



When it first attacks the berries, circular brown spots are noticed, 

 with a somewhat sunken surface, gradually enlarging m size. If 

 there are several spots on the berry, they grow into one another, form- 

 ing a large patch w ith an irregular line. As the disease progresses, 

 the skin of the centre spot may form a scab of a lighter colour — gray- 

 ish and sometimes with a band of vermilion colour outside the centre. 



It will probably be first apparent on the shoots of the vine, on which 

 the spots extend lengthwise, giving them a speckled appearance 

 when abundant. 



It also attacks the leaves and especially the veins and stalks. The 

 stalks of the clusters are often affected too, and when completely 

 girdled, all the berries below the disease-ring remain green, and 

 shrivel up. 



Treatment. — When it is known that a vinery is liable to be attacked 

 by this and other fungous diseases, spraying with Bordeaux mixture 

 should be commenced as soon as the first leaves have fully expanded. 

 The second application may be made after flowering, and the third 

 from 2 to 4 weeks later, according to whether the weather is favour- 

 able to the disease. The Bordeaux mixture may safely be used until 

 the berries are three-fourths their full size. After that the applica- 

 tion may leave a stain which would reduce their market value, and it 

 is better to use the ammonical carbonate of copper about every 10 

 days even after the fruit is fully formed, if the disease is rampant. 



The clusters should be sprayed as well as the leaves, especially when 

 they are young. The reason for several applications is that the spores 

 of the fungus resist successfully every destructive agency, and it is 

 only when they have already germinated that they can be killed. 

 Everything depends upon the thoroughness of the spraying, and each 

 vine should receive about one quart of liquid at each application. 



Besides the use of the Bordeax mixture, it is customary to treat the 

 vines in the winter months when they are bare of leaves and dormant, 

 with the sulphuric acid and sulphate of iron solution, applied by 

 means of a brush or a swab made of rags tied round the end of a stick. 

 The effect on the wood is to blacken it which is looked upon as a test 

 of the thoroughness of the work, and whenever the colour remains after 

 2 or 3 days, a second application should be made. 



Black Rot, 



(Loestadia Bidwellii, V. & R. ; Phoma uvicola, B. & C.) 



The Black rot is even more destructive than the " anthracnose," and 

 besides causing the rotting of the fruit, attacks the leaves and shoots. 



Description. — It is readily distinguished from anthracaose by the 

 centre of the dark disease spots having a number of minute pimples, 



