50 



Diseases of Economic Plants 



which is so pronounced as to injure cider made from affected 

 apples. The chief destruction follows the harvest, though 

 the disease is sometimes found in fruit still upon the tree. 



The Rhode Island Greening, Fall Pippin, Fameuse, 

 Maiden Blush, Tompkins King, and Twenty Ounce are 

 especially susceptible. 



Chief attention should be directed to the prevention of 



Fig. 24. — Pink-rot following scab. After 

 Anderson. 



scab. In storage a dry house, well ventilated, kept at 0° C. 

 (32° F.) gives best rot resistance. 



Another form of pink-rot due to a species of Hypochnus 

 has been described by Eustace ^^ especially upon Baldwins 

 and Rhode Island Greenings. There is no large surface 

 growth of the fungus on the diseased spot, but the rot often 

 extends to the core. 



Powdery-mildew ^^' ^- {Podosphceral eucoiricha (E. & E.) 

 Salm., Oidium). — The general appearance of this mildew 

 is similar to grape mildew; that is, the surfaces of the leaves 



