50 FUXGI AXD rUXGlCIDES 



known as an alternation of the generations of the fun- 

 gus, and two entirely different plants are required for 

 its continued growth. 



This rust is A^ery similar to that which occurs upon 

 the aj)ple, discussed on a previous page. One important 

 preventive measure consists in the destruction of cedars 

 and junipers ; and, probably, sj^raying with fungicides 

 will 23rove to be another. 



The Black Rot 



Sphceropsis malorum 



The fruit of the quince is subject to injury by sev- 

 eral fungi which cause rot. The ripe rot of apples due 

 to GlcBosporium fructigenum often attacks them ; a 

 species of Phoma causes what has been called the ^'pale 

 rot," and other fungi occasionally induce decay. The 

 most destructive of these fruit diseases, however, is the 

 black rot, which usually first appears upon the fruit 

 when it is half grown, or larger, in the guise of a small 

 brownish spot on the surface, generally at the blossom 

 end. The spot increases in size rapidly, and blackish 

 pimples soon appear ; later the skin ruptures at these 

 pimples, and the spores of the fungus escape, to be dis- 

 tributed by the wind. The infested fruit often becomes 

 mummified, and mav remain on the bushes over winter. 

 This fungus also attacks apple and other pomaceous 

 fruits. Quince orchards in the vicinity of apple or pear 

 trees are liable to infestation from them, and vice yersa. 



While it is probable that the use of fungicides will 

 prevent this disease, it usually appears so near the time 

 of harvest that their application may not be advisable. 

 Diseases of this kind may be prevented, to a considerable 

 extent, at least, by clean culture, — the destruction of 

 the rotting or mummified fruits, by means of which the 

 disease is propagated. This may often be supplemented 



