26 The Colorado Experiment Station 
By June 18th. there was no change whatever in the inoculated stems, and 
on June 2 5th. they were in all respects the same as the uninoculated con¬ 
trols; therefore, this germ was eliminated as a possible cause of the 
disease. 
Plant Inoculations of June 21, 1909. 
The cultures used were isolated June 19, 1909. 
Pot No. 11.—Five stems were inoculated by spreading a 4 8 hour 
agar culture of Ps. medicaginis, n. sp. upon the unbroken epidermis, the 
object being to determine whether stomatal infection could be produced 
in this way. After twenty days, isolated brownish spots appeared on the 
inoculated portions of all the plants, and after thirty days these brownish 
areas were black. A microscopic examination of the tissue showed the 
true infection. 
The object of the following inoculations was to determine whether 
Ps. medicaginis, n. sp. was equally pathogenic when isolated from dif¬ 
ferent stages in the progress of the disease. 
Pot No. 12.—One stem was scarified and smeared while a second 
one was inoculated by needle pricks with a culture of Ps. medicaginis, n. 
sp. isolated from a stem which had reached the brown stage of the disease. 
The infection developed in both stems after seven days and by August 1st. 
both were black. 
Pot No 13.—One stem was scarified and smeared while a second one 
was inoculated by needle pricks with a culture of Ps. medicaginis, n. sp. 
isolated from a stem in the earliest stage of the infection when it showed 
the light green, yellow, watery tissue. Both of the stems developed the 
disease in seven days and were black after five weeks. 
Pot No. 14.—One stem was scarified and smeared while a second one 
was inoculated by needle pricks with a culture of Ps. medicaginis, n. sp. 
isolated from a black stem in the advanced stage of the disease. Both 
stems developed the trouble in five to seven days and were black August 1. 
Pot No. 15.—One stem was scarified and smeared while a second one 
was inoculated by needle pricks with a culture of Ps. medicaginis, n. sp. 
isolated from what appeared to be a very recent stomatal infection on the 
stem; there was no indication of the epidermis being broken, and the 
disease occurred in isolated spots around the stomata. Both stems de¬ 
veloped typical symptoms in five to seven days and were black by August 
1st. 
Pot No. 10.—One stem was scarified and smeared while a second one 
was inoculated by needle pricks with a culture of Ps. medicaginis, n. sp. 
isolated from an advanced, black stomatal infection of the stem. Both 
stems developed the disease in five days, and the inoculated areas were 
black August 1st. 
Pot No. 17.—One stem was scarified and smeared while another was 
inoculated by needle pricks with a culture of Ps. medicaginis, n. sp. isol¬ 
ated from a single infected stoma of the stem. Both stems developed very 
good symptoms in four days and were black by August 1st. 
Plant Inoculations of August 25, 1909. 
Cultures used isolated June 1, 1909. 
Pot No. 18.—Stem scraped over the whole internode and smeared 
with a culture of Ps. medicaginis, n. sp. isolated from a diseased stem; 
Sept. 3rd. inoculated area yellowish green color, watery and darker along 
the edge; Sept. 7th. dark brown; Sept. 30th. black. 
Pot No. 19.—Stem scraped in patches and smeared with a culture of 
Ps. medicaginis, n. sp. isolated from a diseased stem. Sept. 3rd. inoculated 
spots plainly visible by the watery, yellowish green patches; Sept. 7th. 
spots dark brown; Sept. 30th. spots black. 
