Diseases oe Beans 
27 
beans affected with anthracnose should never be cultivated while 
the dew is on them or while they are wet from a shower. 
From the affected pods, the disease finds its way to the seed 
where it produces the familiar rusty-red or brown spots. In severe 
cases, the whole seed may be involved, altho ordinarily only a 
slight discoloration is produced on one side. 
Bean Rust 
Bean rust was observed in several fields last year, but it came 
so late in the season that little if any damage resulted. The causal 
fungus, Uromyces appendiculatus, attacks the leaves, stems and 
pods. The rust, as the name implies, can be recognized in its sum¬ 
mer stage by the small, raised, rusty-brown powdery specks on the 
under side of the leaf which rub off easily with the fingers as a 
rusty-brown powder. 
In the winter stage, the specks are black in color and occur 
on both surfaces of the leaf. When found on the upper side, they 
are usually surrounded by a light border, apparently where the 
green leaf tissue has been killed. (See Fig. IV.) While the rust 
is not uncommon, it has rarely been of sufficient economic import¬ 
ance to cause any considerable alarm. Of course, if the attack 
should come early in the season and be very general, the crop 
would suffer in proportion as the vitality of the plant was af¬ 
fected. As the disease winters over on the leaves, the destruction 
of these by burning offers the best means of eradication. 
Bean “Streak” 
For want of a better name, the term “Streak” is used here to 
designate what appears to be a new and undescribed disease of 
beans, which was observed in Colorado for the first time during 
the summer of 1916. Whether this is in reality something new, or 
merely a different manifestation of an old trouble, remains to be 
seen. It attacks stems, leaves and pods, the symptoms on the first 
two of these being much the same as with the bacterial blight. On 
the pods there appear peculiar rusty or orange-brown discolora¬ 
tions in the form of irregular splotches, just as if a brown stain 
had been spattered on them, and had run down in lines or streaks. 
(See Fig. V.) The side of the pod next to the plant is practically 
free from the discoloration, while the outer side may be more or 
less affected over its entire surface. The leaves are destroyed and 
the plants become defoliated before the crop matures. 
It is our purpose to make a study of this disease during the 
coming summer and to determine, if possible, its cause and con¬ 
trol. 
