PLANT DISEASES 253 



or the inside of a cup, several of which may grow up from 

 each half-buried mummy. The spores are ejected from the 

 sacs into the air, to be carried to blossoms, where they 

 cause blight and start the summer development of the 

 disease. Thus in two ways this parasite may continue its 

 existence from year to year. No satisfactory method of 

 controlling it is known. Some promise of success is given 

 by Scott's so-called self-boiled lime and sulfur mixture, 

 which has recently been used as a summer spray for this 

 disease on peaches. 1 



230. Other Fungous Diseases. The apple scab lives over 

 winter on the fallen leaves. It ordinarily attacks the young 

 apples and leaves at about the blossoming time. One 

 spraying just before and one immediately after blossoming 

 are most important for its control, but it is usually neces- 

 sary to spray three times in order to secure clean fruit in 

 regions where the scab is serious. 



Potato scab is planted with the potato. It also lives 

 over winter in the fields where scabby potatoes grew. 

 It may be controlled by soaking the potatoes for one to two 

 hours in a mixture of one pint of formalin to thirty gallons 

 of water, after which they are spread out to dry and are 

 ready to cut for planting. Thirty gallons of the solution 

 is sufficient for treating about twenty bushels of potatoes. 

 After treatment, the potatoes must not be placed in the 

 old crates or bags, as they would become re-infected. 

 They should be planted on land which did not grow scabby 

 potatoes, if possible. The treatment may be of some bene- 

 fit, even if it is necessary to plant on scab-infested land. 



X W. M. Scott, Self-Boiled Lime and Sulfur Mixture as a Promising 

 Fungicide. Bureau Plant Industry, United States Department of Agri- 

 culture, Circular No. 1. 



