ANTHRACNOSE 287 



Only the bark and cambium layer are affected as a rule, the my- 

 celium 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 dis- 

 solves 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 evapo- 

 rates, they are readily distributed by the wind. 



Treatment. Experiments at Washington 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 has been 

 recommended that the plants be so set and trained that they 

 shall have plenty of sunlight and air. I have frequently ob- 

 served neglected plantations, or others in which no pinching 

 of the tips had been done to induce branching, which were very 

 free from this disease. How much of this may have been due 

 to the fact of the long, slender growth of canes and consequent 

 absence of shade and moisture, I cannot say. Old wood should 

 be removed and burned as soon as fruiting is over. The removal 

 of diseased wood in autumn or spring will also aid, but this is 

 seldom a feasible plan, for the fungus is so indiscriminate in 

 its attacks that to remove all diseased wood would often be to 

 remove nearly all prospect of fruit. Experiments at the Ohio, 

 Minnesota and New York State Experiment Stations have all shown 

 that the disease may be controlled by spraying with Bordeaux 

 mixture. The New York experiments,* while showing beyond 

 question that the disease may be controlled, did not show a suffi- 

 cient increase in fruit to cover the expense. It is often recom- 

 mended to treat the bushes with a strong solution of copper sul- 

 phate early in spring, before the leaves start, but their results 



*Bull. 124. 



