252 



ELEMENTS OF AGRICULTURE 



FIG. 130. Brown-rot. 

 Healthy peach above ; 

 diseased below. 



correspond more nearly to the seeds of higher plants, 

 both in method of formation and in function. 



229. An Example of a Fungous Dis- 

 ease. One of the most common fun- 

 gous diseases is the brown-rot of 

 stone fruits, although apples, pears, 

 etc., are also more or less subject to it. 

 It is most destructive on peaches and 

 plums. The chief symptom of this 

 disease is the appearance of a brown 

 rot in the fruit, either while it is still 

 green, or at the time 

 of ripening. As the disease progresses, the 

 entire fruit becomes involved. Tiny gray 

 pustules, or spore masses, break through 

 the skin, and spores by the thousands are 

 cut off in long chains to be scattered by the 

 wind to other fruits, there to reproduce 

 the rot. The rotted fruit soon shrivels and 

 dries, to form the wrinkled mummies that 

 cling to the trees through the winter, or 

 fall to the ground beneath. With the warm 

 spring rains, the mummies on the trees give 

 rise to new masses of spores. These are 

 carried by the breeze to 

 the blossoms and green 

 fruits, and again give rise to the rot. 

 The mummies that fall to the ground 

 usually produce the sexual spores (asco- 

 FIG. 132. Spores of spores) in long, slender sacs (asci), eight 



brown-rot, and a germ- . 



mating spore. spores in each sac. These sacs are borne 



FIG. 131. Brown- 

 rot. The mummies 

 that carry the dis- 

 ease over winter. 



