BACTERIAL LEAFSPOT DISEASE OF CELERY 
By Ivan C. JaggEr 
Pathologist, Office of Cotton, Truck, and Forage Crop Disease Investigations, Bureau 
of Plant Industry, United States Department of Agriculture 
Since 1910 an undescribed bacterial leaf spot disease of celery has been 
under observation. A short paper 1 was read at the 1914 meeting of 
the American Phytopathological Society. The disease has been widely 
distributed in western and central New York State each season, occur¬ 
ring on all varieties of celery commonly grown, including various strains 
of Golden Self-Blanching and numerous varieties and strains of “green” 
celery. Dr. C. H. Coons 2 states that it has been of common occurrence 
in Michigan during the past few seasons. 
The spots are of a rusty brown color, irregularly circular in outline, and 
rarely exceed 5 mm. in diameter (PI. 46, 47). They closely resemble 
the Septoria leafblight spots and can be distinguished with certainty 
only by the absence of pycnidia, which show as black dots in the Septoria 
spots. Occasionally the spots are so numerous as to cause the death of 
many of the older leaves, but usually the injury consists in the disfiguring 
of the foliage and in a possible reduction in growth of the plants. The 
disease seems to be confined to the leaf blades, spots seldom, if ever, 
occurring on the petioles. 
Bacteria have been repeatedly isolated and the characteristic spots 
reproduced by inoculation with pure cultures. In the greenhouse 
during the winter season the organism, sprayed on uninjured leaves, has 
repeatedly failed to give infection although inoculations through needle 
punctures have invariably resulted in characteristic leafspots. Similar 
inoculations by spraying the organism from pure cultures on uninjured 
leaves have resulted in abundant infection during the summer season 
under field conditions. 
The causal organism is a short rod, measuring when stained from 
3-day agar slants 0.44 to 0.87 ft by 0.87 to 1.74 ft. It has one to several, 
usually one to three, polar flagella. 
In the study of the cultural features the methods given by Smith 3 
were followed as far as possible. All observations were made on cultures . 
held at 20 ° C. Growth on standard nutrient agar is rather rapid, colo¬ 
nies being evident in dilution plates in 48 hours or less; at the end of 3 
days surface colonies are 2 to 5 mm. in diameter, grayish white, translucent, 
1 Jagger, Ivan C. A bacterial leap spot disease OF CELERY. (Abstract.) In Phytopathology, v. 
4, no. 6 , p. 39 S» 1914- 
* Coons, G. H., and Nelson, Ray. the plant diseases of importance in the transportation of 
fruits AND vegetables. Circ. 473-A, Amer. Railway Perishable Freight Assoc., P..32, fig. si. 1918. 
8 Smith, Edwin F. bacteria in relation to plant diseases. 3 vol. Washington, D. C. 1905-1914. 
Journal of Agricultural Research, 
Washington, D. C. 
xs 
(185) 
Vol. XXI, No. 3 
May 2, 1921 
Key No. G-228. 
