THE APPLE 



common on the neglected, fallen fruit, which is a source of infec- 

 tion to the tree. It may first appear as a very small spot, generally 

 near the bud end or calyx of the fruit, then spreading rapidly over 

 the entire fruit. It may be brown in color at first, but it later 

 changes to black, hence its name. It differs from bitter rot in not 

 having the characteristic fungous tissue. It may be readily inter- 

 changed between bark and fruit, and therefore is a very dangerous 

 disease. The remedies given are thorough spraying with Bordeaux 



mixture and atten- 

 tion to the bark, as 

 described in a pre- 

 vious part of this 

 chapter (p. 212). 



Blotch {Phyllos- 

 ticta solitaria). The 

 first evidence of the 

 disease on the fruit 

 is a very small, incon- 

 spicuous, light-brown 

 blotch, which, under 

 a hand lens, has 

 the appearance of a 

 stellate collection of 

 brown fibers just be- 

 neath the epidermis. 

 The blotch, spread- 



Fig. 99. Black rot. (University of Maine) 



ing radially, increases 

 in size until it attains 

 a diameter of from 1 to | and sometimes 1 inch, and becomes 

 darker in color. The advancing margin is irregular and jagged 

 and has a fringed appearance. On very young apples the points 

 of infection occasionally show as small water-soaked areas, and in 

 wet weather there may be a yellowish, gummy exudation from the 

 spots. Where the spots are numerous, they often coalesce and form 

 large blotches, which may cover half or more of the apple. The 

 fungus kills only the superficial cells (the epidermis and outer 

 parenchyma), so that the continued growth of the uninvaded tissues 

 beneath results in a cracking: of the diseased areas. The cracks 



