Apr. 15, 1921 
Bacterial Spot of Tomato 
145 
COTYLEDON INOCULATION 
Infection on both upper and lower surfaces of the cotyledons was 
readily obtained by spraying a flat of seedlings with a water suspension 
of the organism in an atomizer. This infection consisted of small, sunken, 
silvery or lead-colored, well-scattered spots visible only on one surface 
of the cotyledon. Secondary infection of cotyledons in flats of seedlings 
as a result of ordinary sprinkling irrigation was similar in appearance 
and of common occurrence (PI. 25, B). Primary cotyledon lesions 
resulting from seed-borne infection are discussed below. 
SEED INOCULATION 
On February 12 three small gauze packets (A, B, and C) of tomato 
seed were dipped in a water suspension of the bacteria from agar slant 
cultures. Lots A and B were dried at once, and lot C was immersed 
five minutes in a 10 per cent solution of formalin, rinsed thoroughly, and 
dried. Lot D consisted of similar seed, not inoculated. Parts of these 
seed lots were then planted the next day in flats in the greenhouse, and 
the seedlings were carefully examined at intervals for cotyledon infection. 
The results are presented in Table IV. 
Table IV .—Seedling infection 
Seed 
lot. 
Treatment. 
Num¬ 
ber of 
plants. 
Number showing in¬ 
fection after— 
Per¬ 
centage 
show¬ 
12 
days. 
21 
days. 
27 
days. 
ing in¬ 
fec¬ 
tion. 
A. ... 
Inoculated . 
283 
J 95 
277 
186 
0 
24 
26 
8 K 
0 
n 
rlo. 
0 
C.... 
Inoculated arid treated in formalin. 
O 
O 
O 
D 
Not inoculated. 
O 
O 
O 
0 
Thus, about 10 per cent of the inoculated seed yielded infected seed¬ 
lings, whereas uninoculated seed and sterilized seed yielded disease-free 
seedlings. The primary cotyledon lesions were characteristically differ¬ 
ent from the cotyledon lesions described above. The primary lesions 
were larger and fewer in number, frequently only one on a cotyledon, 
more commonly on the dorsal surface, and very often both cotyledons of 
an affected seedling bore such lesions in corresponding positions. Pri¬ 
mary lesions were black, shiny, depressed areas, 2 to 8 mm. in diameter, 
at first visible 011 only one surface of the cotyledon (PI. 25, C). Such 
lesions were often found associated with the adhering seed coat and fre¬ 
quently occurred at the tip of the cotyledon or at the notch in the margin 
where the seed coat had remained attached. In cases where such lesions 
occurred on the midrib, distortion of the cotyledon resulted. 
