New York AGRICULTURAL EXPERIMENT STATION. 217 
turn yellow. Sometimes, even in severe attacks, the leaves show 
scarcely any tendency to become yellow. 
The diseased spots are plainly visible on both sides of the leaf, 
but most conspicuous from the upper surface. In color, they are 
brown or black. Their general shape is circular with the boundary 
irregular and not sharply defined. The size of the spots varies from 
a mere speck to 1.5 or 2 mm. in diameter. They are irregularly dis- 
tributed over the leaf. Many of the spots, even on leaves which 
have lain on the ground several days, show no signs of Pseudopeziza 
apothecia. The fungus is somewhat slow in fruiting. Under a hand 
lens the apothecia first appear as small shiny elevations, amber col- 
ored or nearly black. In this condition they contain asci and para- 
physes, but no ascospores. Soon the shiny elevations crack at the 
summit, the crack gradually widening until the apothecium becomes 
cup-shaped, flat or even elevated at the center, while the edges of 
the ruptured epidermis stand up all around the margin. Ascospores 
may be found at any time after the rupturing of the epidermis, but 
usually not before. They are hyaline, non-septate, elliptical, 8-11 
x 4-6 and there are eight in each ascus arranged in sub-biseriate 
fashion.°® In 1907, mature ascospores were found at Geneva on 
June 7, but they were not yet plentiful. However, the spring of 
1907 was a backward one—about ten days later than usual. It 
seems probable that, at Geneva, the first ascospores mature about 
June 1. After this date they may be found at any time until frost. 
Leaf spot often appears in alfalfa fields on soil which has not 
previously grown alfalfa. When this happens in fields which have 
been strewn with soil from another alfalfa field for the purpose of 
securing inoculation with nodule bacteria the leaf spot infection is 
satisfactorily accounted for, since without doubt spores of the leaf 
fungus may be disseminated with soil. But it is noteworthy that 
the writers have observed severe attacks of leaf spot in fields on 
which no alfalfa soil had been used and where there were no other 
alfalfa fields in the vicinity. In such cases, the infection must come 
either from spores sown with the seed or from host plants of other 
species. Both methods are possible. It is highly probable that the 
disease may be transmitted with the seed. Red clover is attacked 
by Pseudopeziza trifolit (Bernh.) Fckl. which is considered by some 
botanists to be identical with P. medicaginis while others regard it 
*Tilustrations of Pseudopeziza medicaginis on alfalfa are given by Chester 
(14, p. 82); Combs (17); Briosi and Cavara (8, No. 262); and Saccardo 
(Fungi Italici, No. 1390). 
