248 
Journal of Agricultural Research 
V6I. XXIV, No. s 
EXPERIMENTAL INOCULATIONS 
: As a result of these experiments it has been conclusively proved that at 
least 13 species of grasses are subject to attack by the identical virus 
causing sugar-cane mosaic. Undoubtedly there are many more, but with 
the limited space at the disposal of the writers it was impossible to carry 
on the work on a larger scale. Species which have thus far given nega¬ 
tive results may in the future prove to be susceptible. Many factors have 
entered which no doubt have diminished the chances for infection fol¬ 
lowing these inoculations. Optimum growing conditions for many of the 
grassy do not prevail at Washington. Sometimes whole series of inocu- 
^tipajs including known susceptible control plants failed, owing to un¬ 
known causes. Insect carriers became parasitized by other insects or 
died as a. result of unfavorable conditions in the greenhouse, and they 
were not available or were not in a normal state when the plants were in 
the best condition for inoculation. In other words, the positive results 
attained must naturally carry more weight than the negative results, 
a^d in listing grasses as not susceptible it is merely meant that they did 
not/becKune infected in these experiments. 
: Though it is possible that there is more than one mosaic disease affecting 
grasses, and there is some reason for believing this to be so, this paper 
is, concerned with one onjy, the well-known type which has recently proved 
so destructive to sugar cane in Porto Rico and the southern United 
States. , 
The plants tested and found susceptible are shown in the following list: 
Cultivated crops* 
: Perennial-:— . 
Sugar cane... .Saccharum officinarum. 
Annuals— 
Com........... .Zeamays. 
Sorgliuni. Holcus sorghum, 
i , Pearl millet..... Pennisetum glaucum. 
Ornamentals: 
Pe^^ — 
■ Eulalia... Miscantkus sinensis. 
Wild grasps: 
r , Perennial— 
, , Wild sugar cane. ... Saccharumnarenga (S. P. I. No. 38332).* 
' Annuals— 
Bull-grass... Paspalumboscianum. 
: ' Crab-grass... Syntherisma sanguinalis. 
: Yellow foxtail.... Chaetochloa lutescens. 
Giant foxtail. Chaetochloa magna. 
Barnyard grass.. Echinochloa crusgalli, 
' Panicum... Panicum dichotomiflorum, 
Brachiaria.... Brachiaria platyphylla. 
* A vancty of Saccharum narenga is cultivated in China, according to Mr. Frank N. Meyer 
