1893.] MICROSCOPICAL JOURNAL. 199 



cies is C.tuberosiis which was found growing from decaying veg- 

 etables in France. 



There can be no question that the ultimate rotting is caused 

 by bacteria; several have been isolated. Among them Bacillus 

 subtilis^ a very common species. A portion of raw beet was 

 taken out, inoculated with diseased beet placed in an incuba- 

 tor at 42° C. The following morning it was covered over with 

 the growth of a bacillus. A strong odor of boiled beets was 

 given off, while the beet was black. This bacillus had devel- 

 oped to the exclusion of everything else. A second inoculation 

 was made with a pure culture of the organism, but the results 

 were not very decisive. The raw beet did not take on the sud- 

 den blackening, nor was the odor so decided. Some of the 

 other bacteria found are shown (Plate IV, figs, x, xi, xv, xvi, 

 xviii). Several other saprophytic fungi have been found, 

 among them a species of Fusarium forming white patches. 

 This appears to be Fusarium bet&s which has been compared 

 with a Fusarium on a beet kindly sent me by Mr. Ellis. The Fus- 

 arium is a secondary growth and is in no way responsible for 

 the disease (Plate IV, figs. 2, 3, and 4). A Fusarium unidenti- 

 fied was found a few years ago on decaying beets in cellars. 

 It may be responsible for some of the cellar rot. 



VI. — Summary, 



The principal fungus diseases of the sugar beet are Beet 

 Rust, White Rust of Beets, Spot Disease of Beets, Root-rot and 

 Beet Scab. All of these diseases with the exception of rust oc- 

 cur in Iowa. Beet Rust is caused by Uromyces betas, and is closely 

 related to bean, oats and other rusts. White Rust of Beets 

 forms Avhite blotches on the leaf, which consist of a large num- 

 ber of small spores. The fungus appears to be Gystopus blitii, 

 which occurs on some of the Amaranths. Spot Disease of Beets 

 manifests itself by producing round spots, at first not larger 

 than a pin head, these spots become larger with age and finally 

 cause the leaf to become black in color. The disease is caused 

 by a fungus known as Cercospora betas. The disease can no 

 doubt be checked by Bordeaux mixture or ammoniacal carbon- 

 ate of copper. . Root- rot is caused by a fungus which appears to 

 be related to Rhizoctonia betae, a fungus discovered some years 

 ago in Germany. It appears to have done some injury to the 



