STEM BLIGHT 
A New Bacterial Disease of Alfalfa * 
By WALTER G. SACKETT. 
HISTORY AND DISTRIBUTION. 
In May of 1904, Hon. J. L. Chatfield, who resides at Gypsum, 
Ea,gle County, Colorado, observed that while the stand of alfalfa on 
his ranch was good, much of it was shorter than it should be at 
that time of the year, and that here and there plants were dying. 
He reported this condition to the Experiment Station at Fort Col¬ 
lins, and in response to his request, Professor Paddock and Profes¬ 
sor Gillette visited his fields. They examined a number of plants, 
but they were unable to give any decisive answer as to the exact 
cause. Occasionally, worms were found in the crowns and in the 
roots, and by splitting the latter lengthwise, numerous dark streaks 
could be traced through the tissue. A few crowns were blackened, 
as well as some of the stems, but this discoloration was looked upon 
as due, possibly, to insect work, although no specific insects could 
be found at that time. 
The following year, there was practically none of the trouble 
to be seen in the whole valley, which has an area of at least five 
thousand acres, more than one half of which is in alfalfa. 
The next year, however, 1906, the conditions were worse than 
ever before and the universal complaint among the farmers was 
that there was “something wrong with the alfalfa.” Professor 
Paddock again visited Gypsum, and at this time the blackened stems 
were very abundant and much more conspicuous than when he was 
there before. He brought back specimens of this material to the 
college and a microscopic examination satisfied him that, in all 
probability, the trouble was of bacterial origin. As a result of these 
findings, in November, 1906. Professor Paddock (1) called atten¬ 
tion to a new alfalfa disease occurring in certain parts of Colorado, 
which was different from any previously described malady and 
which, from all appearances, was not related to either leaf spot or 
mildew. 
The disease has spread with increasing severity until at the 
present time it is a very difficult matter to find one acre of alfalfa 
land in the whole valley which is entirely free from the trouble. 
The loss in tonnage for the first cutting is estimated at eighty per 
cent, or the crop is only one-fifth of what it was in former years. 
The disease became so serious in 1907 that it was thought advis- 
* This is an abbreviated edition of Bulletin No. 158, entitled A Bac¬ 
terial Disease of Alfalfa. The former includes detailed description of the 
causal bacterium and inoculation experiments. Bulletin No. 158 will be 
sent on request. 
(1) Press Bulletin No. 28, Colo. Exp. Sta. 
