4 The Colorado Experiment Station. 
that city. Quarantine must be established or an epidemic is sure to 
follow. Just so with diseases in our fields. It should behoove every 
farmer to see to it that his field is free from infection and to com¬ 
pel his neighbor to be equally vigilant. 
The diseases treated are: 
Bacterial Disease of Alfalfa, Page 4. 
Pear Blight, Page 6. 
Soft Rot of the Sugar Beet, Page 14. 
Black Rot of Cabbage, Page 15. 
Blight of Potato, Tomato, Egg Plant, and Tobacco, Page 19. 
Bacteriosis of Beans, Page 21. 
Wilt of the Cucumber, Cantaloupe, and Squash, Page 22. 
BACTERIAL DISEASE OF ALFALFA 
PRELIMINARY REPORT. 
In November 1906 , Prof. Paddock* called attention to an 
alfalfa disease occuring in certain parts of Colorado, 
which was different from any previously desciibed mal¬ 
ady, and which, from all appearances, was not related to either 
leaf spot or mildew. Gross examination of the affected stems and 
roots and subsequent microscopic examination satisfied him that in 
all probability the disease was of bacterial origin. During the past 
summer, 1908, a careful study of the disease has been undertaken 
both with field and laboratory studies, and a technical bulletin is 
now in preparation, describing both the diseases and the causal 
organism. Our present investigations have confirmed the pre¬ 
liminary work of Prof. Paddock and have shown the cause of the 
disease to be due to a germ of the bacillus type. 
Description oe the Disease. —At a distance, the disease 
can be recognized by the short, sickly growth of the first crop and 
the marked absence of that rich, deep green color and succulent 
appearance of a thrifty stand. Many of the plants do not get over 
eight inches to a foot high by the time of the first cutting. A close 
examination of the stems show's them to be shriveled and blackened 
for two to three inches up from the ground. The infection seems 
to attack the plants next to the soil and to work up the stem. As 
the disease progresses, it produces a watery, semi-transparent, 
brownish appearance of the tissue which turns black with age. By 
running the thumb nail along the stem, it is possible to scrape up 
under the delicate surface skin a little yellowish, watery blister, the 
content of which is a sticky, stringy liquid, yellow in color, and 
alive with bacteria. This liquid frequently oozes out on the stems 
*Press Bull. 28, Colo. Expt. Sta. 
