DISEASES OF THE APPLE 249 



thought the fly speck and sooty blotch were two separate 

 and distinct diseases, but further study has revealed the 

 fact that the fly speck and the sooty blotch are stages of 

 the same fungus. This disease is occasionally found on the 

 pear. Fly speck disease is quite superficial, and it appears as 

 a number of small black specks, quite regular in outline. 

 Each individual spot is about the size of a small pin head, 

 and in the earlier stage it is still much smaller. A mass of 

 the fungus gives the fruit the appearance of being covered 



FIG. 107. The apple blotch. 



with soot. So far as injuring the fruit is concerned none 

 occurs, but the discolored fruit is hard to sell, and conse- 

 quently reduces the profits. Spraying for the scab will be 

 effective in controlling the fly speck. 



Fire Blight. The fire blight is one of the most serious 

 diseases of the apple. It also is very injurious to the pear. 

 It is a contagious disease of bacterial origin. The fire 

 blight is caused by very small organisms called bacteria. 

 They are rod-shaped and motile. They multiply by simply 

 dividing and they increase very rapidly. Immense num- 



