150 Journal of Argicultural Research voi. xxi.no. • 
OVERWINTERING AND DISSEMINATION 
Whether or not the causal organism of bacterial spot overwinters in 
the soil has not been proved as yet. It has been found, however, that 
the organism lives over winter on tomato seed and that such seed gives 
rise to infected seedlings. 
Laboratory tests have proved that the organism will endure long 
periods of desiccation upon tomato seed. In one test not yet com¬ 
pleted the organisms have endured over 11 months of such desiccation. 
Tomato seed immersed in a water suspension of the bacteria, dried, 
and then planted in sterilized soil gave rise to numerous infected seed¬ 
lings. The primary cotyledon lesions were very characteristic and 
fairly easily differentiated from secondary infection. 
Commercial seed was then tested in a similar manner. A number of 
lots of commercial seed from the fruit in a large field known to have been 
severely diseased with the bacterial spot were tested by planting in flats 
of sterilized soil in the greenhouse during April and May of 1920. This 
seed had been machine-cleaned from the tomato pulp in a canning fac¬ 
tory during the 1919 harvest, and in this process of seed separation and 
cleaning there was ample opportunity for contamination of the seed 
with the bacteria from fruit lesions. The results of two series of such 
tests are presented in Table VII. 
Table VII .—Test of commercial seed in sterilized soil 
Seed lot. 1 
Number 
of plants. 
Number of 
plants with 
infection. 
Pri¬ 
mary. 
Second¬ 
ary. 
g 
/?•• 
309 
O 
O 
..\b.. 
490 
4 
18 
0. 
. if- 
318 
5 
4 
.. 
lb.. 
364 
6 
6 
10 
. h ■ • 
271 
1 
2 
lb.. 
509 
6 
4 
IO. .. 
336 
0 
1 
. 
lb.. 
557 
2 
6 
21. .. 
.if*-- 
334 
0 
0 
lb.. 
490 
10 
36 
22... 
3 2 4 
6 
17 
... . 
\b.. 
500 
8 
40 
21... 
... h- 
299 
4 
3 
lb.. 
404 
4 
1 
2C . . 
fa.. 
281 
4 
1 
.lb.. 
374 
6 
0 
26. .. , 
330 
10 
26 
... 
lb.. 
397 
5 
0 
Total. 
6, 887 
81 
io d 
1 Part of seed lot designated as "a" planted Apr. 14; results taken 31 days later. Part designated as “b” 
planted Apr. 24; results taken 26 days later. 
