A Bacterial Disease oe Aeealea 31 
We shall continue this part of the investigation with the same, 
as well as additional varieties, since the only practical way of test¬ 
ing out the disease resistance of these different kinds of alfalfa is 
to grow them under actual field conditions on infected soil, where 
natural agents are at work. We shall introduce, also, legumes 
other than alfalfa, in order to determine the susceptibility of these 
to the disease, so that we may be in a position to recommend other 
crops as substitutes where the land is so badly infected as to make 
profitable alfalfa growing no longer possible. 
prevention and treatment. 
Where the areas under cultivation reach such tremendous pro¬ 
portions as the alfalfa fields on the mountain ranches, all schemes 
for soil sterilization are obviously impracticable at the outset. The 
same may be said of the use of germicides to be applied to the plants 
either in the form of sprays or otherwise, for even though some 
such means should be discovered by which the infection could be 
prevented, the cost would undoubtedly make it prohibitive. Ob¬ 
viously, then, as stated before, the only practical way of combating 
and controlling the blight is by the introduction of resistant varie¬ 
ties. What is being done in this direction has been mentioned 
before. 
Our field observations during the past year seem to indicate 
that immunity to the disease is closely related to resistance to late 
spring freezing. On the one hand, those plants which were severely 
injured by the late spring frost were, without exception, the first 
to show the disease and were the worst infected later in the season : 
on the other hand, those varieties which grew from hardy stock and 
which suffered only slightly from the frost, were more nearly free 
from the blight. This coming year we shall endeavor to determine 
whether the relation between disease resistance and frost resistance 
is a constant one, and if it proves to be such, then we shall attempt 
to stamp out the trouble by securing frost resistant varieties. 
In the meantime, we recommend, as a means of control, that 
the frosted alfalfa be clipped as soon as one is reasonably certain 
that there is no more danger from frost. By this means, the frost 
split stems, in which the disease appears to originate, will be gotten 
rid of, thus affording an opportunity for the early growth of a new 
cutting. Prof. P. Iv. Blinn, who has charge of the Experiment 
Station work at Rocky Ford, informs the writer that this practice 
of early clipping to remove the frost bitten shoots, which retard 
growth, is rapidly growing in favor among the farmers in his 
locality. 
