THOMAS: INFECTION OF APIUM GRAVEOLENS 9 
greenhouse. The season was favorable for vigorous development 
of the fungus and as a result the spots soon ran together and 
caused the collapse of the entire leaf. Consequently the method 
of counting spots could not be used. The total weight of celery 
produced would be inaccurate as an index of the severity of the 
attack, since the varieties differ normally in the weight of the 
mature plant. However, certain general conclusions can be 
drawn from the gross appearance of the plants at the end of the 
season. The plants were inoculated by atomizing a single plant 
of each variety on August 5. On October 29, at the time of digging, 
the variety Golden Self Blanching had been so severely damaged 
that only a few living leaves remained. During the latter part of 
the season while the plants were blanching, a soft rot was asso- 
ciated with the late blight on all of the varieties. This was 
especially severe on the Golden Self Blanching and seemed to 
follow in areas of dead tissue killed by the Septoria, especially on 
old leaves. The unusually wet period at that time would have 
favored the development of the various saprophytes which are 
present under such conditions. Of the varities other than Golden 
Self Blanching, there was no easily recognizable difference in 
susceptibility. Easy Blanching (Henderson’s) seemed to with- 
stand the blight and subsequent rot slightly better than the other 
varieties. White Plume, a self blanching form, was not notice- 
ably poorer than the green varieties. An accurate method of 
estimating the amount of infection would probably have shown 
differences which could not be noted with certainty from the 
general appearance. 
Infection tests on various Umbelliferae and a considerable 
number of miscellaneous plants have shown that the species of 
Septoria under consideration here is very limited in its host range, 
if not entirely restricted to the single species, Apium graveolens, 
and its variety rapaceum. Parsley (Petroselinum sativum) has 
been inoculated repeatedly in the greenhouse under controlled 
conditions but no sign of infection has been produced. The 
tests included the plain leaved parsley (two varieties), the curly- 
leaved type and the Hamburg or turnip-rooted parsley. The 
plain parsley was grown in the field in a row adjacent to heavily 
infected celery but infection was never found on any of the 
