MOSAIC OF STTGAK CANE AND OTHER GRASSES. 15 
OTHER HOSTS. 
A number of other grass plants are known to be subject to the 
mosaic disease, but apparently they are attacked with difficulty 
and only under conditions favorable to the disease. Among these 
hosts are corn, sorghum, rice, millet, crab-grass, foxtail, and Panicum. 
Probably the list of susceptible plants is much larger, but up to the 
present time opportunity for testing others has not been had. In 
the case of corn, rice, and millet, we have no experimental proof that 
the diseases are the same, but must depend upon field observations. 
If not the same, the disease must be very similar, since the leaf 
symptoms are identical. The characteristic streaked and spotted 
appearance of the leaves is present in all attacked plants. 
With regard to sorghum, crab-grass, foxtail, and Panicum our 
evidence is conclusive and proves that the infectious material or virus 
is the same for all of these plants. Sorghum seed of the Early 
Amber, Sugar Drip, and Japanese Kibbon varieties was sown in a 
bed at the quarantine greenhouse at Washington, where diseased 
plants of 17 different varieties of sugar cane were growing. When the 
sorghum plants were about half grown, practically all of them began 
to produce mottled leaves and continued to do so until they went to 
seed. 
The seed was saved from these sorghum plants to determine whether 
the disease is transmitted to the next generation in the true seed. 1 
The leaf symptoms in these greenhouse plants were exactly like the 
symptoms on sugar-cane leaves. Plants arising from the same batch 
of seed used in the greenhouse experiment cited above but planted 
elsewhere and not exposed to the disease did not show the phenomenon 
but produced healthy leaves of uniform color. The crab-grass, fox- 
tail, and Panicum came up as volunteer plants in the quarantine 
greenhouse. Scores of stools of these weeds were allowed to mature 
for observation and identification. Every plant became infected 
and exhibited the typical leaf symptoms. Some half dozen other 
species of wild grasses were present in the greenhouse, but they were 
not attacked. All of the wild grasses were abundant outside of the 
greenhouse, but in spite of an assiduous search in the vicinity not 
a single infected plant could be found. The conclusion to be drawn 
from these observations is obvious. We are not dealing with similar 
mosaic diseases of these various graminicolous hosts, the viruses of 
which are specific for each host, but with one and the same disease. 
The existence of other host plants, especially the common wild 
grasses, would appear to be one of the most alarming of the recent 
developments in the problem. It is needless to say that the control 
A __^ 
i This seed was planted in flats. At the present time, three weeks after germination, no sign of the mosaic 
has appeared. 
