14 THE BITTER EOT OF APPLES. 



OCCURRENCE ON VARIOUS HOSTS. 



The first bitter-rot fungus was described in 1854 (Berkeley) as 

 growing on grapes. Some years later the same writer described a 

 fungus causing ripe rot of the apple. Berkeley in some later papers 

 describes the ripe-rot fungus (under various names) as occurring on 

 grapes, apples, peaches, and nectarines. In 1871 Berkeley, referring 

 to a manuscript description of a fungus growing on grapes (Glaeo- 

 sporium uvicola), takes occasion to say that in his opinion it is the 

 same as the fungus causing ripe rot of peaches and nectarines (Glceo- 

 spo Hum last icolor Berk.). He states that "where grapes are grown 

 in the same house with stone fruits the malady may spread upward," 

 which ma}* be taken to imply that he considered that the ripe-rot fun- 

 gus of grapes ma}' cause the disease of peaches and nectarines. He 

 further emphasizes their probable identity by saying (p. 1163): " Both 

 on grapes and stone fruits the spores of the fungus are very variable 

 in size, so that no stress can be laid on mere measurement." 



Von Thiimen (1887) added the pear and the apricot to the list of 

 hosts. Galloway, in 1890, demonstrated for the first time that the 

 ripe-rot fungus of the grape, when transferred to the apple, caused the 

 ripe rot or bitter rot of the apple, and vice versa. Miss Southworth, 

 in 1891, confirmed these results. 



Halsted, in 1892, published the results of a large number of experi- 

 ments in which he had inoculated fruits with spores from different 

 ripe-rotted fruits to determine whether the numerous forms of ripe 

 rot or bitter rot were really due to the same fungus. His experiments 

 seemed to prove that the same fungus caused the ripe rot of the apple, 

 grape, peach, pear, pepper, tomato, and eggplant. The fungus was 

 found to grow on bananas, quinces, lemons, and beans, in addition to 

 the other hosts mentioned. 



Chester (1893) corroborated Halsted's results so far as the tomato, 

 grape, pepper, and apple were concerned. He came to the same con- 

 clusion as Halsted — i. e., that the fungus on the apple, grape, tomato, 

 and pepper is biologically the same species. Alwood (1891) states 

 that all pomaceous fruits are attacked by Gla>osj)orium fructigemim 

 Berk. During the last year Spaulding grew the fungus successfully 

 on squash. (PI. IV, fig. 6. See also PI. IV, fig. 5, showing the 

 fungus on the pear.) 



From the evidence at hand it appears that this fungus can adapt 

 itself to numerous hosts. It seems probable that all the forms are one 

 and the same species, but it will be necessary to develop the perfect 

 or ascus stage of many of them before any positive statement on this 

 point can be made. 



