192 
Journal of Agricultural Research 
Vol. I, No. 3 
plants were watered well, and the leaves were sprayed with sterile water 
and left under the cage overnight, so that the stomata would open. The 
following day the growth from two-day-old agar cultures was shaken up 
well in sterile water and sprayed on the upper and lower surfaces of the 
leaves. The plants were watched carefully for two weeks, but no trace 
of the disease was ever seen. The experiment was repeated some months 
later with the same result. 
Some cultures were sent to Garland, Utah, and Mr. H. B. Shaw, who 
had charge of the experiment station there during the season of 1909, 
inoculated the leaves of sugar beets growing in the open field. There, 
as well as in the greenhouse, the plants became infected very readily. 
Mr. Shaw sent some of the leaves to the sugar-plant laboratory at Wash¬ 
ington. Upon examination swarms of bacteria were found in the black¬ 
ened areas. Mr. Shaw also took portions of the diseased leaves, including 
the spots, and inoculated other leaves with them. Fifty per cent of the 
leaves treated in this way became spotted. 
The most striking feature of this affection as it occurs in the green¬ 
house from inoculations is the black color of the spots and streaks, for 
they stand out prominently against the green of the leaves. These 
leaves never become soft, but bend over at the badly sunken spots, lose 
their turgidity, and finally die from drying out. If the petiole is inocu¬ 
lated, it frequently happens that the leaf blade will drop at a sharp angle 
from the infected area in less than two weeks. 
INOCULATIONS WITH ORGANISM ISOLATED FROM NASTURTIUM LEAF 
Inoculations with the organism isolated from nasturtium leaves were 
made into leaves of some rather old nasturtium plants growing in pots 
in the greenhouse. After several days small, watery-looking areas 
became visible, and the tissue within these areas became discolored and 
shriveled, resembling in all particulars the original spots from which the 
organism was obtained. A microscopic examination of the tissue within 
the diseased areas thus produced showed the cells to be filled with many 
active bacteria. Check plants having leaf surfaces pricked with a sterilized 
needle presented no indication of diseased spots. From the observation 
of inoculated plants it was noticed that the general appearance of the 
leaf spot changed considerably during the different stages of its devel¬ 
opment. Leaves of a healthy young nasturtium plant showed the 
effects of needle-prick inoculations within 48 hours, the tissue at first 
becoming slightly darker in the infected areas and presenting a water- 
soaked appearance. These spots gradually increased in size, becoming 
4 to 6 mm. in diameter, while the tissue within became dry and brown¬ 
ish in color and often brittle enough to crack (PI. XVIII). A dropping 
out of this diseased tissue frequently followed, and finally the whole 
leaf turned yellow and fell from the stem. 
