BUTLER AND KULKARNI. 259 



produced chiefly on the upper surface of the leaves and are therefore 

 more readily reached by the mixture than if they were confined to 

 the under surface, as often occurs in potato blight. Experiments 

 to test the value of spraying have not been possible, as the disease 

 has not been severe at Pusa since 1909, when its study was com- 

 menced. The expense of spraying makes it a method of treatment 

 which could only be practicable in very severe attacks and it is 

 doubtful if it could be brought within the means of the ordinary 

 cultivator in India. 



In the early stages of attack, all spotted leaves must be removed 

 and destroyed. This will be effective in delaying the period of 

 severe attack and giving the conns time to form. 



Corms kept for seed should be gone through at intervals and 

 any that show signs of rotting, removed. At the time of planting 

 only sound corms should be selected. This is probably the most 

 important point in the control of the disease, as provided that a 

 sufficient rotation is practised, the fungus is likely to disappear 

 from the soil unless reintroduced in infected corms. 



Planting in shady localities should be avoided, as there is no 

 doubt that the severity of the attack largely depends on the humi- 

 dity of the air. 



Dec-ember 1912. 



