7 
A Bacterial Disease of Alfalfa 
Out of twenty-one infected stems examined and plated at dif¬ 
ferent stages of the disease, thirteen gave pure cultures of this 
colony in the Petri dishes. In seventeen plates, it was the dominant 
colony. Platings from five different leaves gave pure cultures in 
three cases and in four out of five the above colony was the most 
abundant. In other words, pure cultures were obtained in 62 per 
cent of the original isolations and in 81 per cent this white colony 
was dominant. In two out of twenty-six isolations or in seven per 
cent, it was absent. Plates made from the moist or freshly dried 
exudate, as a rule, gave pure cultures of the same organism. 
An examination of the following notes, made in connection 
with some of the isolations, may be of interest in showing with 
what degree of purity the organism can be isolated from field 
material. 
Plates made from material collected at Gypsum, Colorado, May 
25, 1909. Plated in Nutrient Agar May 27, 1909. 
I. Petiole.—Culture pure; growth after 72 hours; culture picked 
up 6-1-09. Colony round, smooth, grayish white, glistening, slightly 
raised. Stained film preparation from four day old colony; short rods, 
medium thick, mostly single, occasionally in twos, slightly curved and 
wedge shaped; stain readily with ordinary aqueous fuehsin. 
II. Leaf.—Culture pure; characteristic white colony; growth after 
72 hours; culture picked up 6-1-09. Colony and stained film same as 
Petiole above. 
III. Stem Tissue—New Infection.—Culture pure; characteristic 
white colony; growth after 72 hours; culture picked up 6-1-09. Colony 
and stained film same as Petiole above. 
IV. Stem Tissue.—Culture pure; characteristic white colony; growth 
after 72 hours; culture picked up 6-1-09. Colony and stained film same 
as Petiole above. Orange colonies appeared on June 5th; picked these up. 
V. Stem Tissue—Black.—Culture mixed; growth after 4 8 hours; 
cultures picked up 6-1-09. Yellow colonies dominant; few white colonies 
which resemble those described from petiole. 
VI. Exudate Scale No. 1.—Culture pure; growth after 72 hours; 
culture picked up 6-1-09. Characteristic white colonies same as petiole 
but germs themselves seem shorter, less curved and wedge shaped. Later 
observations have shown this germ to be the same as the petiole culture. 
VII. Exudate Scale No. 2.—Culture pure; growth after 72 hours; 
culture picked up 6-1-09. Characteristic white colonies; germ same as 
that described from Exudate No. 1. 
In all probability, all of the above characteristic white colonies 
were the same. Slight differences in staining seemed to make some 
difference in the size and shape of the organism itself. In every 
case the germ is a short, medium thick, motile rod with rounded 
ends and with a tendency to produce slightly curved forms which 
show granules on staining. 
Plates made from material collected from the Experimental 
Plats at Gypsum, Colorado, June 11, 1909, and plated June 14, in 
nutrient agar. Notes taken June 19, 1909. 
