LEAF-SPOT OF ALFALFA AND RED CLOVER. 29 
Two days later, when one of the apothecia was crushed out in water, 
asci containing spores apparently mature were found. The leaf was 
then supported over an agar surface. In two hours a large number 
of spores were discharged, which germinated promptly. At this 
time the young alfalfa shoots had hardly emerged from the mulch 
of the debris of the previous season's growth. 
On May 6 spots began to appear on the alfalfa foliage of some of 
the plats under observation. When the spotted leaves were decol- 
orized, characteristic Pseudopeziza spores with germ tubes penetrat- 
ing the epidermal cells were found in nearly all the spots. 
A search of the overwintered foliage discovered a large number of 
fresh-appearing apothecia developed on leaf areas that had been 
diseased the previous year. When the overwintered leaves were 
placed over agar plates, a large number of viable ascospores were 
caught. 
Fragments of overwintered leaves bearing apothecia were placed 
over ten marked leaves of a healthy alfalfa plant in the greenhouse, 
and the plant was kept in a moist chamber for 24 hours. On May 17 
seven of the ten marked leaves showed more or less of the charac- 
teristic Pseudopeziza spotting. 
Five or six of these overwintered leaves bearing apothecia were 
placed on the ground under a rank growth of alfalfa plants in the 
greenhouse. The plants were then sprayed, but not covered to pre- 
vent evaporation of water from the foliage. On May 21 the alfalfa 
foliage in the vicinity of these overwintered leaves was found in- 
fected with leaf -spot. 
On March 31, 1917, overwintered alfalfa leaves bearing leaf-spot 
lesions were collected in an alfalfa plat. At this time no spores 
could be found in the apothecia. These leaves were kept in a moist 
chamber for a week, care being taken to soak them in water twice 
a day to remove the products of decomposition. At the end of the 
week asci with mature spores had developed in the old apothecia. 
Thus, it appears evident that Pseudopeziza medicaginis survives 
the winter on diseased foliage which escapes decay. When the 
weather becomes sufficiently warm in the spring and moisture is 
provided by protracted rains or the shelter offered by the young 
growing foliage, new asci develop apparently in the old apothecia 
and, in addition, new apothecia are produced around the old one 
(PL II, A). The spores thus produced furnish the primary infec- 
tion in the spring. 
Apothecia producing spores indistinguishable from those of Pseu- 
dopeziza trifolii were found on overwintered clover leaves in the 
spring of 1916 in northern Wisconsin, but since no inoculations were 
made with these spores, their identity was not determined. However, 
