14 BULLETIN 1029, U. S. DEPARTMENT OE AGRICULTURE. 
of the hypocotyl. In the first case invasion by the fungus takes place 
before or during germination. In rare cases the testa remains at- 
tached to one of the cotyledons, and delayed infection may thus occur. 
The disease appears as shriveling of the infected tissue of the cotyle- 
don without much loss of color, beginning usually at the margin and 
progressing toward the petiole. Pycnidia later appear in the 
shrunken tissue, their development being materially hastened in 
humid environments. Infection at the base of the hypocotyl usually 
takes place after germination, inoculum coming from the fungus 
within the seed coat, which ordinarily remains below ground, closely 
adjacent to the crown. In the same way nongerminable infected seeds 
may be the source of inoculum for near-by healthy seedlings. This 
has been shown to take place by planting such seeds alternately in the 
furrow with healthy viable ones. In the case of hypocotyl infection, 
the disease appears above ground as a gradual shrinkage of the suc- 
culent tissue, progressing upward and ultimately causing a collapse 
of the plant. As in the case of cotyledon infection, pycnidia later 
appear in the shrunken tissue, their development likewise being en- 
hanced by moist environment. Under greenhouse conditions where 
a temperature of 70° to 75° F. and a relative humidity of about 60 to 
70 per cent were maintained, the first signs of disease usually ap- 
peared in 8 to 10 days after planting, and other primary lesions con- 
tinued to develop for three to five weeks. As a rule, cotyledon lesions 
appeared first and hypocotyl infections a few days later. Out of 
doors, where there is a greater range in environmental conditions, the 
progress of the disease may be delayed. 
RELATION OF RAINFALL TO THE DEVELOPMENT OF THE DISEASE. 
A study of the effect of variation in the depth of rainfall on the 
development of the disease in the seed bed was made during the 
spring and summer of 1919 at Madison, Wis. Untreated seed of 
the Wisconsin Hollander variety, lot No. 2-18 previously referred to, 
was sown on May 14: A small percentage of the pods from which 
this seed was taken had shown black-leg lesions, and in greenhouse 
tests about 2 per cent of the seedlings had developed primary hypo- 
cotyl infections. The seed bed was divided into four plats, which 
were, respectively, handled as follows: Plat 1, exposed to natural 
weather conditions; plat 2, exposed as plat 1 and sprinkled several 
times each week during dry weather; plat 3, covered with a cold- 
frame during rains ; plat 4, covered every evening and during rainy 
weather. The last treatment was devised to reduce the amount of 
dew which might form upon the plants. As a matter of fact, how- 
ever, under the climatic conditions which prevailed during the trial, 
this artificial inclosure led to a greater accumulation of moisture 
upon these plants in plat 4 than upon those in plat 3. The protected 
