64 Journal of Agricultural Research voi. iv, no. i 



of infection. In many of the badly infected orchards, however, they 

 had been removed both from the trees and from the ground. 



The fungus from all the sources mentioned was positively identified 

 as Glomerella cingulata not only by microscopical observations and 

 spore measurements but by spore germination and growth on artificial 

 media as compared with germination and growth from spores from 

 actual cases of bitter-rot of the fruit. Also in all cases sound, sterile 

 apples were inoculated with spores from pure cultures, the typical 

 bitter-rot disease was brought about, and the fungus reisolated. Thus, 

 the spores from every source of infection discussed as such in this paper 

 were proved to be those of the bitter-rot fungus. 



SUMMARY 



(i) Previous writers have shown that the apple bitter- rot fungus 

 {Glomerella cingulata) may pass the winter in mummied apples of the 

 preceding year and in bitter-rot cankers from which the early infections 

 of the following season may come. Other plants also may be possible 

 sources of infection. 



(2) The writer has shown that in apple orchards where the infec- 

 tions have been severe the fungus may winter over on almost any cank- 

 ered or dead parts of the tree, including the Illinois apple-tree canker 

 due to Nummularia discreta; dead tips of fruit spurs; dead parts of 

 limbs due to injury by freezing or to death of roots; branches injured 

 by mechanical means; cankers caused by the pear-blight organism 

 {Bacillus amylovorus) ; twig cankers caused by the apple-blotch fungus 

 {Phyllosticta solitaria) . 



(3) Eradication of cankers greatly reduced the number of early 

 infections of the disease, though removal of all small dead parts, such 

 as dead tips of fruit spurs and small mechanically injured places, is, of 

 course, practically impossible. 



LITERATURE CITED 

 Alwood," W. B. 



1902. Orchard studies. XV. The bitter rot of apples. Va. Agr. Exp. Sta. Bui. 

 142, p. 252-279, illus. 

 BuRRiLL, T. J., and Blair, J. C. 



1902. Bitter rot of apples. 111. Agr. Exp. Sta. Bui. 77, p. 351-366, illus. 

 Clinton, G. P. 



1902. Apple rots in Illinois. 111. Agr. Exp. Sta. Bui. 69, p. 189-224, illus. 

 ScHRENK, Hermann von, and Spaulding, Perley. 



1903. The bitter rot of apples. U. S. Dept. Agr. Bur. Plant Indus. Bui. 44, 54 p., 



9 fig., 9 pi. 

 Scott, W. M. 



1906. The control of apple bitter-rot. U. S. Dept. Agr. Bur. Plant Indus. Bui. 



93. 33 P-. I fig-. 8 pi. 

 Shear, C. L., and Wood, Anna K. 



1913. Studies of fungus parasites belonging to the genus Glomerella. U. S. Dept. 

 Agr. Bur. Plant Indus. Bui. 252, nop., 4fig., 18 pi. 



