24 
Colorado Experiment Station 
3. Burn refuse from diseased plants. 
4. Do not allow animals to roam over infested fields, for they 
carry the organisms to non-infested fields. 
Celery. 
Blight. There are two distinct blights of celery, the early blight 
and the late blight. Remedial measures for the two are similar. 
Early Blight. This blight makes its appearance in the early 
stages of the plant’s growth. The outer leaves are attacked first, the 
disease is manifested by grayish-green spots, almost circular in out¬ 
line and with slightly raised borders. Later the spots may coalesce 
and exhibit an ashen gray color. Finally the entire leaf withers and 
dies. Spores produced from these spots are readily blown to other 
plants and set up the disease anew. 
Late Blight. In general, this blight resembles the early blight of 
celery. It may follow early blight in the same field. As compared 
with the early blight, the spots are less regular in outline and with 
yellow interiors instead of ashen gray. As in the early blight, the 
disease begins on the older, outer leaves, passes to the inner leaves, 
until no salable part is free from the injury. Severe attacks mean 
worthless celery, since the bunches will not keep in the market or 
storage. Even slight attacks on the leaves are undesirable and the 
price is usually cut by market buyers. The disease organism lives 
over winter on trash of diseased plants. The seeds from diseased 
fields practically always carry the fungus. Wet weather makes the 
late blight severe by facilitating spore dissemination. 
Control: 
1. Disinfect the seed before planting, by first soaking it for % 
hour in warm water, but not in hot water. Then soak for I /2 hour in 
a solution of corrosive sublimate, 1 part to 1,000 parts of water. This 
solution can usually be purchased from druggists already prepared. 
Corrosive sublimate is very poisonous. 
2. Seed that is two or three years old, if of good germinative 
power, may best be used for seeding purposes, since the disease or¬ 
ganisms on the seed are usually dead after that length of time. 
3. Do not set plants from the seed bed that are the least spotted. 
Burn diseased plants and rubbish from the field in the fall. 
CEREALS. 
. Wheat. 
Stinking Smut. This is the most common and most destructive 
smut of wheat. It is exclusively a disease of the grain. At harvest 
the contents of the grain are completely replaced by black powdery 
masses of spores having a disagreeable odor. The affected grains are 
enclosed by the chaff and appear darker than healthy kernels. On 
