Oct 27,1923 
A Bacterial Stripe Disease of Proso Millet 
153 
of the plants the growing point and upper unfolding leaves were killed. 
The killed portions of the expanded leaves were dry and brown, while 
the killed, inclosed, young leaves were soft, brown, and disintegrating. 
Lesions extending down the sheaths and stem to the root produced a 
browning at the crown where the plants readily broke away from the 
root. There were abundant separate lesions on blades and sheaths, and 
many of the leaves looked brown and ragged where the tissue had split 
at the lesions. The other two varieties showed abundant infection, but 
not so much as Early Fortune. This plot was practically destroyed by 
the disease. 
ISOLATION AND INOCULATION EXPERIMENTS 
Microscopic examination of the free-hand sections through leaf blade 
and sheath showed that there were large numbers of bacteria in the 
lesions. 
Isolations from fresh material were made in two ways: (1) Scales of 
exudate were scraped off into +15 broth and plates poured from the 
broth; (2) small pieces of leaf tissue were dipped into 95 per cent alcohol 
for a few seconds, then placed in mercuric chlorid solution (1 :iooo) for 
one to two minutes, washed through three sterile water blanks, crushed 
and transferred to sterile broth from which the plates were poured. 
Twelve isolations were made at different times and all gave practically 
pure cultures of a white organism which, when used for inoculation, pro¬ 
duced typical lesions of the disease on proso. Transfers from these iso¬ 
lations were labeled cultures I, II, III, IV, V, etc., and cultures I, II, and 
V were used for cultural and morphological studies. 
Inoculations were made by spraying plants in the greenhouse with 
water suspensions of the organism made from 2-day-old to 4-day-old agar 
slant cultures. Sprayed plants were held in damp chambers for from two 
to four days. Controls were sprayed with sterile water and held under 
the same conditions as inoculated plants. 
In three to four days the lesions appear on the inoculated leaves as 
water-soaked streaks a millimeter in diameter and from one to several 
centimeters in length (PI. 3, B). The lesions are sometimes along the 
margins and sometimes through the leaf blade between the veins. Lesions 
may extend from the blade down onto the sheath. Some plants rotted 
at the surface of the soil where the inoculum had run down and collected. 
In one.inoculation with culture I, where there were a great many infec¬ 
tions, the leaves turned yellow or dried up. Controls under identical 
conditions kept a healthy green color and showed no signs of infection. 
Reisolations from these lesions gave characteristic white colonies which 
again produced narrow, water-soaked lines 3 to 4 inches long on the leaf 
blades. 
Out of 15 inoculations of Early Fortune, n produced good typical 
lesions of the bacterial disease, while 2 were unsuccessful because the 
damp chambers were not tight and the plants could not be kept moist. 
The other two inoculations were made with isolation No. IV, which never 
produced any lesions and was discarded as not being the organism to 
which the disease is due. 
Six inoculations were made on sorghum (African, Orange, and an 
unidentified variety) with cultures I, II, and V. No lesions appeared 
on any of the plants, although proso plants inoculated at the same time 
and kept in the same damp chambers showed abundant infection. Acme 
