4 
Colorado Experiment Station 
At about the same time that complaints were received of this 
trouble on field peas, a similar blight made its appearance on garden 
peas in Northern Colorado. 
In the pages which follow, will be found a description of this 
disease and of the microorganism which has been found to be 
responsible for the trouble. 
HISTORY AND DISTRIBUTION 
The first occurrence of the disease was noted by Mr. E. H. 
Thomas, county agent for the San Luis Valley, on May 27 , 1915 , 
in the garden of Mr. Wm. Ollinger, Hooper, Colorado. In this 
instance, garden peas for family use had been planted in soil which 
had been very heavily manured, and when the vines were 3 to 6 
inches high, they began to turn brown, dry up and die. The owner 
attributed the trouble to too much manure or to excessive alkali. 
However, Mr. Thomas was inclined to look upon these facts as of 
secondary importance, and accordingly sent the writer several 
specimens of affected peas at this time. 
The general appearance of the plants, with their characteristic 
bruised, water-soaked leave's and stems, suggested, at first sight, 
bacteria as a very probable cause of the trouble, and subsequent 
experiments have confirmed this supposition. . 
The next locality where the disease was observed was in 
Blanca, where, on June i, 1915 , Mr. Thomas found the same 
trouble attacking field' peas; during the next few days he noted 
the blight in the vicinity of San Acacio, Antonito, Monte Vista and 
Center. In fact, we are reasonably safe in saying that it was gen¬ 
eral on the early planted peas over practically the entire valley. 
The writer visited the localities mentioned above on June 3 
and 4 . The peas varied considerably in size, ranging from 3 inches 
in height to 8 or 10 , and in the two days that we spent in looking 
over the fields, we did not find more than two or three tracts that 
were entirely free from' the trouble. The severity of the attack 
appeared to differ in the different localities, due possibly to the fact 
that the infection had progressed more rapidly and was farther 
advanced in some places than in others; now and then we came 
across a field where only an occasional plant was affected, but again 
tliere were many where it was almost impossible to find a 
healthy one. 
Mr. Thomas visited one of the worst affected fields at Antonito 
on July 22 nd. From the roadside, there appeared to be a full stand 
of good vines, but upon closer examination it was found that at 
least one-third of the plants were missing. The average branch¬ 
ing of the remaining plants was heavier than normal, there being 
many with three or more vines, while under ordinary conditions 
only two would have been present. The old infection had dis- 
