164 BOTANICAL GAZETTE [MARCH 
their account of the synonymy of the organism. They called it 
Dothidella ulmea (Schw.) E. and E., thereby placing it among the 
Dothidiales, although they acknowledge that it is ““anomalous on 
account of its ascigerous cells assuming the characters of peri- 
thecia.”” In 1915 THIESSEN and Sypow (38), in a monograph of 
the Dothidiales, excluded it from that group and referred it back 
again to Gnomonzia in the Sphaeriales, where it had previously been 
placed by von Toten. In addition to these various names, the 
fungus has been much confused by American plant pathologists 
and mycologists with an organism causing a leaf spot of European 
elms in Europe, Sysiremma Ulmi (Schleich.) Thiess. and Syd. 
(38), to which it has a superficial resemblance, and it has often 
been collected and reported under one or another of various lists 
of synonyms pertaining to that fungus. 
In 1gor and 1902 STONE and SmitH (37) from Massachusetts 
reported attempts at controlling the disease by spraying with 
Bordeaux mixture, referring to the fungus as Dothidea Ulmi 
(Duv.) Wint., a synonym of Sysiremma Ulmi, in the first paper, 
and as Dothidella ulmea, a synonym of Gnomonia ulmea, in the 
second, although they made no reference to the discrepancy. In 
1910 Gtissow (21) reported it from Canada as extending back 
upon the petioles of young shoots to their tips, which twisted 
downward and finally died. He stated that in no case did the 
young shoots so infected recover. In this same year CLINTON (8) 
from Connecticut reported that by July or earlier some trees had 
shed almost all their leaves. He stated that these trees later put 
forth a new crop of foliage which was entirely free from the disease, 
but that the other trees, not so severely infected in the beginning, 
showed all their leaves more or less affected, and shed them con- 
tinuously throughout the season. He stated that when defoliation 
was most severe the young branches of the season also had fallen 
off. This latter observation confirms that made by Gissow in 
Canada. The writer has seldom seen so severe an infection as 
either of these, although in some localities the disease is severe 
enough each year to cause an incessant dropping of leaves through- 
out the summer and fall, which is a far from desirable characteristic . 
in a lawn and avenue tree like U. americana. 
