THE BITTER ROT 35 



jecting threads. These spores are blown off by the 

 wind, or washed downward by rain. When one of them 

 lodges u2)on another apple, where sufficient heat and 

 moisture is present, it germinates by sending out a little 

 tube, and may thus start the disease in a new situation. 

 If the mycelium of the fungus running through the 

 apple is carefully examined, one will see at frequent 

 interyals on the threads small spore-like bunches, simi- 

 lar to those shown in B, Fig. 19. From these other 

 mycelium threads may start. In the same figure a ger- 



FIG. 18. SECTION OF PUSTULE. 



A, Mass of fuugus threads and cells; B, spore-bearing threads; C C, skin of apple 



ruptured by the fungus. 



minating summer spore is seen in C, and one of the pus- 

 tules already referred to in A. 



This same fungus attacks grapes, and Dr. Halstead 

 has recently found that it will develop upon pears, 

 peaches, egg plants and i")eppers. Consequently it seems 

 to have a wide range of hosts, and general clean culture 

 is evidently important as a method of preventing its 

 injuries. 



Treatment. — The first step toward the successful 

 prevention of this disease is the removal and burning of 

 the mummied apples on the trees. This should be done 

 during winter. It would be desirable, also, to rake up 

 and burn, or bury, the fallen fruit and surrounding rub- 



