248 



FARM FRIENDS AND FARM FOES 



BROWN ROT SPORES 



DEVELOPING 



Magnified 



blown upon the damp fruit send out their germinating 

 tubes into the tissues where they grow, branching in all 

 directions. These branches absorb the cell contents. In 

 this way the green tissues are broken 

 down, the light green color is turned 

 to brown, and the so-called rot ap- 

 pears. On the outside, the fruit first 

 turns brown in one or two places, then 

 more and more of the surface appears 

 affected, until finally the whole surface 

 shows the injury. 



Soon after the fruit has thus be- 

 come discolored, it is likely to show 

 a curious velvety coating more or 

 less grayish in color that is made 

 up of millions of tiny spores. They 

 are produced by the threads of mycelium that have been 

 developing amid the tissues of the fruit. Under the micro- 

 scope they are easily seen to resemble the figures below. 



These spores are blown everywhere 

 by the wind and serve to spread the 

 disease very rapidly. A single affected 

 fruit may furnish millions of spores for 

 the wind to sow broadcast over the 

 surrounding country. 



Unless the diseased fruits are re- 

 moved, many of them remain upon the 

 tree. They shrivel slowly into dry 

 and mummied fruits inside which the 

 threads of mycelium develop into 

 blackish bunches that correspond in a 

 way to winter spores and enable the 

 fungus to survive the winter, and to produce a new crop 



BROWN ROT 

 a, spores ; b, spores ger- 

 minating; magnified 



