22 
Colorado Experiment Station 
soil clean by crop rotation, he should be just as caref ul that diseased 
seed does not undo all his work of preparing the soil. 
Advisability of Disinfecting- Diseased Seed. —There is hard¬ 
ly a group of plant diseases known which can be more readily 
and . completely controlled than those carried on the outside of 
seeds. Considering the cost of treatment, which seldom exceeds 
two cents per bushel, the farmer can ill-atford to use anything but 
clean seed. Whenever any noticeable number of diseased plants is 
seen in a field, there always occurs a material loss of the crop, hence 
prompt means of eradication should always be taken, depending upon 
the disease present. Not all diseases can be controlled by treatment of 
the seed as, for instance, wheat rust, mildews or blights, or even corn 
smut, but on the other hand, such diseases as the cereal smuts, certain 
anthracnoses and various vegetable diseases are best controlled by seed 
disinfection. 
It is not always an easy matter to determine whether or not fungi 
are attached to seeds wanted for seeding purposes, but it is very un¬ 
wise to use seed known to have come from diseased fields, even in small 
amounts. 
Seed treatment is very simple and can be performed with a very 
small outlay of materials and a minimum of trouble. The principle 
of seed treatment is to kill fungous spores lodged on the surface of the 
seed by the application of a disinfectant solution. The solution must 
be strong enough to destroy the spores, but effect no injury to the 
grain. For this purpose formalin and corrosive sublimate are most in 
use. Formalin is a solution of formaldehyde gas in water. When 
purchased for seed treatment, it should possess 40% concentration. 
All druggists have this strength in stock (and it is sold at 50 to 70 
cents per pound). Corrosive sublimate is a severe poison and when 
employed for seed disinfection, the seed should not be fed to live¬ 
stock. It is diluted in the proportion of 1 part to 1,000 parts of water. 
Corrosive sublimate is sold in the form of a powder and readily dis¬ 
solves in lukewarm water. 
Diseases for Which Seed Treatment Should Be Used. 
Bean. 
Bean Anthracnose. This disease affects all above ground parts 
of the plant. The greatest injury occurs on the pods usually, whei-o 
the appearance of the disease is marked. It is manifested by spots 
that are round to oval in shape, discolored, dark and sometimes pink¬ 
ish and surrounded by a reddish zone or margin. On the leaves the 
spots are similar in appearance to those on the pods; they occur on 
the large veins, generally on the under surface. In advance stages, 
the leaves may bo eaten through by the fungus. Frequently the seeds 
themselves show marked discoloration as a result of serious attacks on 
the pods, and as a general rule the seeds carry the disease over the 
winter to next season’s crop. 
