Anthracnose 253 



is badly injured but only the stems and leaves are said to be 

 attacked. 



The mycelium, creeping between the plant cells, causes their 

 destruction and the consequent appearance of the dead spots. Only 

 the bark and cambium layer of the stems are affected as a rule, the 

 mycelium rarely entering the wood to any extent. Near the center 

 of the spots the mycelium threads unite to form a dense tuft, made 

 up of the slender club-shaped basidia on which the spores are borne. 

 These basidia are formed beneath the surface, but soon rupture it 

 and form a minute globule outside, being covered with a clear, 

 gelatinous substance which holds the spores in place. When brought 

 in contact with water, this substance readily dissolves and allows 

 the spores to float away. These germinate readily in water, and 

 many of them soon find lodgment in healthy portions of tissue and 

 form new centers of infection. If the water which sets them free 

 from the inclosing mass soon evaporates, they are readily distributed 

 by the wind. 



Treatment. Experiments have shown that the spores germinate 

 most readily in pure water. It has also been observed that the spread 

 of the disease is more rapid in wet weather than in dry weather. For 

 these reasons it is advisable to so set and train the plants that they 

 shall have plenty of sunlight and air. Excessive pinching of the tips, 

 causing the formation of a dense head, is to be avoided. Neglected 

 plantations or others in which no pinching is practiced are some- 

 times free from the disease. Old wood should be removed and 

 burned as soon as fruiting is over. The removal of diseased wood 

 is seldom feasible, since all parts of the plant are likely to be at- 

 tacked. This should be done in setting young plants, however, 

 if it is impossible to get plants which are entirely free from the 

 disease. Experiments in different states have shown that careful 

 spraying will prove effective and in some cases profitable. Bordeaux 

 mixture in the proportion of 4-4-50 is advised before the leaves 

 appear, again when the shoots are six inches high and a third time 

 just before the blossoms open. It should be remembered that the 

 mycelium remains alive in the canes during winter, and that spray- 

 ing can in no way cure the disease. It can only prevent, if thor- 

 oughly done, the germination of spores as they are produced, The 



