BACTERIAL SPOT OF TOMATO 1 
By Max W. Gardner, Associate in Botany , and James B. Kendrick, Assistant in 
Botany , Purdue University Agricultural Experiment Station 
INTRODUCTION 
During recent years the tomato crop in the north central States has 
been affected with a spot disease of the fruit which was recognized by 
pathologists as distinctly different from any of the well-known tomato 
fruit spots. W. A. Huelsen, of the Purdue Agricultural Experiment 
Station, noted the prevalence of this disease in the Indiana canning 
tomato crop of 1918. In the 1919 crop the disease again became preva¬ 
lent in Indiana, and the present study was begun in the fall of 1919 and 
continued throughout the winter and spring. The present work deals 
mainly with the symptoms of the disease, the isolation, pathogenicity, 
cultural characters, overwintering, and dissemination of the causal bac¬ 
teria, and their relation to the host tissue. Certain phases relative to the 
mode of fruit infection under field conditions are to receive further study. 
The relation of this tomato disease to the bacterial spot of pepper which 
occurs in Florida has received only preliminary study. Apparently the 
causa, organisms are identical. 
THE DISEASE 
NAME 
This disease as it occurs on the fruit has been called “canker” by Coons 
and Nelson (4, p . 48 ) 2 and “scab,” “fruit scab,” and “black scab” by 
McCubbin (9, p . 15). It seems advisable, however, to adopt the name 
“bacterial spot” for the disease, since the term canker has been used for 
another tomato disease, and since the term scab is hardly applicable to 
the foliage lesions. The name bacterial spot has also been used for the 
related disease of peppers (15). 
HOSTS 
The hosts of this disease are tomato and pepper. Foliage infection has 
been obtained on potato. Bacterial spot has been found on the following 
tomato varieties in the field: Yellow Plum, Greater Baltimore, Stone, 
Century, Arlington, Norton, Marvel, and Columbia. Foliage inoculation 
has been successful on all tomato varieties tested. This list comprises the 
following varieties: Bloomsdale, Magnus, Paragon, Landreth, Delaware 
Beauty, John Baer, Hummer, Improved Trophy, Coreless, Success, Red 
‘Contribution from the Botanical Department of Purdue University Agricultural Experiment Station. 
LaFayette, Ind. 
The writers wish to acknowledge their indebtedness to Prof. H. S. Jackson for helpful suggestions received 
throughout the course of this investigation. 
a Reference is made by number (italic) to “Literature cited,” p. 155-156. 
Vol. XXI, No. 2 
Apr. 15, 1921 
Key No. Ind.-p 
(123) 
Journal of Agricultural Research, 
Washington, D. C. 
xk 
