154 
Journal of Agricultural Research 
Voi. xxr, No. s 
To determine more accurately the effect of these mercuric-chlorid 
treatments upon the viability of the seed, germination tests similar to 
those recorded in Table VIII were repeated, using soil flats in the green¬ 
house. The results are presented in Table X. 
Table X .—Effect of mercuric chlorid upon germination 
Treatment. 
Number 
of seeds. 
Percentage of germination 
after — 
Remarks. 
5 days. 
7 days. 
13 days. 
HgCl 2 , 1: 2,000. 
IOO 
54 
87 
97 
No retardation. 
HgCl 2 , 1: 3,000. 
100 
47 
67 
93 
Do. 
HgCl 2 , 1: 4,000. 
IOO 
12 
58 
85 
Do. 
Control. 
IOO 
87 
93 
HgCL, 1: 2,000. 
200 
01 . K 
Do. 
Hp'CL. i: 2.000. 
200 
y x ‘ 0 
q 6 
Do. 
HffClo. 1 : a. 000. 
200 
y 
00 
Do. 
* f • •••••*• • • • • • 
Control . 
200 
y 
87 
Thus, the weaker strengths of mercuric chlorid have no deleterious 
effect upon the germinabilitv of the seed nor the vigor of the seedlings. 
Pending subsequent tests, disinfection of tomato seed in i to 3,000 mer¬ 
curic chlorid for five minutes followed by thorough rinsing in running 
water is, therefore, recommended as a control for tomato bacterial spot. 
To summarize, it may be pointed out that: (1) Seed treatment in hot 
water (55 0 C. for 10 minutes), in hot formaldehyde (2.5 per cent at 50° 
for 5 minutes), and mercuric chlorid 1 to 1,000 for 5 minutes was injurious 
to the seed; (2) 5 per cent and 10 per cent formaldehyde exerted no 
injurious effects but were not reliably effective; (3) mercuric chlorid 1 to 
2,000, 1 to 3,000, and 1 to 4,000 gave perfect sterilization and exerted 
no injurious effects. 
SUMMARY 
Bacterial spot of tomato is a typical spot disease of the fruits, stems, 
and foliage. 
Practically all varieties of tomatoes are susceptible. Peppers and 
potatoes are also susceptible. 
> The disease as it occurs on tomato fruit was first reported from Ten¬ 
nessee, Illinois, and Michigan. It was called “canker.” It has a wide 
geographic range. 
The worst damage is due to the fruit lesions. The disease is also 
destructive among seedlings and occasionally as a foliage trouble in the 
field. 
The fruit lesions are small, black, scablike spots, usually superficial, 
sometimes crateriform. Leaf lesions are at first translucent, later black 
and greasy with translucent margins, and are not usually limited by the 
veins. 
