Apr. is, i9ai 
Bacterial Spot of Tomato 
151 
Thus it is apparent that 81 out of 6,887 seeds, or about 1 per cent, 
gave rise to diseased seedlings. This proves that the organism occurs 
on commercial seed and lives over winter thereon and that such seed 
yields diseased seedlings. As a means of dissemination about 1 seed 
out of every 100 should be expected to give rise to a center of infection, 
and with such seed the disease will be carried far and wide. Field obser¬ 
vations indicate such to be the case. The disease was found in fields in 
Georgia planted with seed sent from the North. These fields were not 
in tomatoes before, and it seems quite likely that the disease was intro¬ 
duced with the seed. Furthermore, the disease appeared in plant beds 
in clean soil in southern Indiana planted with seed obtained from a 
diseased field the previous season. This seed was hand-cleaned by 
cutting the fruits in two and rubbing the halves over a screen. This 
process undoubtedly facilitated seed contamination from fruit lesions. 
It is evident, therefore, that the disease may be transported long dis¬ 
tances and introduced into new fields and localities by contaminated 
seed. 
Judging from the outbreak of the disease among the seedlings in the 
Georgia fields and in the plant b ds at Campbellsburg, Ind., it seems 
quite likely that considerable spread of infection may occur in the plant 
beds before the plants are transplanted to the field and that the disease 
may be carried long distances and introduced into new fields with dis¬ 
eased transplants. The disease has been found epidemic early in the 
season in an Indiana field planted with Georgia plants. 
Local spread of infection has not been carefully studied. The oc¬ 
currence of secondary infection in the greenhouse flats indicates that 
infection is spread by the sprinkling process. Little or no secondary 
infection occurred on plants which were not sprinkled. In the field 
infection is undoubtedly spread by the splashing of rain, by wind-blown 
rain, and by surface drainage water. 
The relation of insects to fruit infection in the field still remains to be 
worked out. That fruit infection occurs through insect punctures 
seems almost unquestionable. Whether or not the insect inoculates 
the fruit at the same time the wound is made has not been determined 
Greenhouse tests indicate that infection may occur through fresh punc¬ 
tures already made, as well as in punctures made with an inoculated 
instrument. 
In summary it may be said that: (1) The organism lives over winter 
on the surface of the seed; (2) among seedlings grown from commercial 
seed, about 1 m every 100 may bear primary cotyledon lesions and serve 
as a center of infection; (3) the disease is disseminated by contaminated 
seed and by diseased transplants. 
29669°—21 -5 
