(yOI.ORADO Pr.ANT DISEASES 
37 
thus selected in a seed plot of ground that has never grown beans 
before. Use the seed from this plot to plant the larger fields. Seed 
for the seed plot must be selected in the field for diseased seed cannot 
be detected as they come from the thrasher. 
Where ever practical all diseased vines, should be destroyed by 
burning. Avoid cultivating beans when they are wet with dew or 
rain. 
Anthracnose (Colletotrichum lindemuthianum) (31), (34), (35) 
— Anthracnose of bean only recently made its appearance in Colo- 
rado. In 1918 it was very prevalent and did much damage. In 1919, 
due perhaps to the very dry season, it was of little importance. 
The disease is first noticed on the seed, leaves and stem of young 
plants. Dark reddish brown spots are produced on the stems and 
larger veins on the under side of the leaves. Reddish-brown circu- 
lar, sunken spots are formed on the pods. The fungus works its 
way from these spots through the pod and into the seed. Seed 
infected in this way carry the fungus over from year to year. 
The spores of the fungus produced in the center of the reddish 
brown spots are glued together by a sticky material, which is dis- 
solved as soon as a drop of moisture touches it. Any disturbance of 
the plant while wet with dew or rain would tend therefore to spread 
the disease. For this reason beans should never be cultivated while 
they are wet from rain or dew. 
Since the disease is carried over by diseased seed the same proc- 
ess of seed selection recommended for control of bacteriosis is 
applicable to the control of anthracnose. 
Certain varieties of beans are said to be more resistant to anthrac- 
nose than others but recent work indicates that there are two or 
more specialized forms of the fungus causing anthracnose and that 
a variety may be resistant to one form but very susceptible to 
another. This is a question that should be further investigated. If 
different specialized forms of the fungus exist it is very important 
to know how many there are and where they occur. 
Stem Blight (RhLzoctonia sp.)— Beans throughout the state were 
seriously injured the past year by a fungus which attacked the stem 
just beneath the surface of the ground. Brick-red to dark brown 
irregular lesions were produced which often girdled the entire stem. 
These interfered with the transportation of food and greatly reduced 
the vigor of the plants. In many cases the injury was sufficient to 
kill the entire plant. The fungus causing the injury was not 
