126 
Journal of Agricultural Research 
Vol. XXI, No. 2 
A bacterial leaf spot of pepper was first reported by Heald and Wolf 
(7, p. 42) from Texas in 1912. The causal bacteria were not described. 
In the same year a bacterial leafspot and blight of peppers was found by 
Jackson (£, p. 274) in Oregon. While the bacteria isolated were not 
yellow, yet the colonies somewhat resemble those of the tomato organism. 
In 1917 SherbakofT (15, p, 79R) worked with a bacterial spot of pepper 
in Florida which is very likely due to the same organism as bacterial spot 
of tomato. He isolated and proved the pathogenicity of a yellow organ¬ 
ism which, however, he did not describe. 
In 1918 the senior author noted the fruit lesions of what appeared to 
be pepper bacterial spot on southern-grown fruit in the Chicago market. 
In 1920 Link and Ramsay isolated a yellow organism from this so-called 
pepper scab and suggested that the disease was identical with the tomato 
bacterial spot. From a Florida-grown pepper fruit secured in the Chicago 
market by Link and Ramsay, which showed typical scab lesions similar 
to those illustrated by Sherbakoff, the authors have isolated a yellow 
organism resembling in culture the tomato bacterial spot organism. 
Inoculation of tomato plants with this organism gave typical leaf lesions, 
and inoculation of pepper plants with one of our tomato strains has 
resulted in leaf lesions resembling those described and illustrated by 
Sherbakoff. 
Therefore, it seems safe to assume that the causal organism of pepper 
bacterial spot is identical with that of tomato bacterial spot. However, 
since we have not worked out the cultural characters of the organism 
isolated from pepper and since we have not found the pepper disease 
occuring naturally in Indiana, except in an experimental field, we shall 
confine our attention in this work very largely to the disease as it occurs 
on tomatoes. 
SYMPTOMS 
On the tomato fruit the disease causes scab-like lesions which may 
occur at any point on the surface (PI. 24, B). These first appear as 
blackened, raised points or dots surrounded by a water-soaked border. 
Older lesions assume the form of black, slightly raised, superficial spots 
with a lobed or dendritic margin and a water-soaked border or halo (PI. 
24, A). From 1 to 2 mm. in diameter these lesions may enlarge until a 
diameter of 6 to 8 mm. is attained (PI. 24, E). The central portions of 
these lesions, composed of disintegrated mesocarp tissue, soon collapses 
and sinks, and its surface becomes fibrous and rough. In the larger 
lesions the water-soaked margin is absent and the centers may become 
so sharply sunken that the lesion resembles a circular dry pit or crater 
with the ruptured epidermis about its margin (PI. 24, D). Such lesions 
have apparently ceased to enlarge. Absence of the water-soaked border 
may be taken as evidence that peripheral enlargement has ceased, and 
it is apparent that fruit lesions may be checked at any stage of their 
development. Actively enlarging lesions are not found on mature fruit. 
