8 THOMAS: INFECTION OF APIUM GRAVEOLENS 
ized in its choice of a host by inoculating plants from the following 
groups: (a) plants of the family Umbelliferae, including varieties 
of celery; (b) miscellaneous plants, nearly all of which are known 
to be hosts of Septoria. ‘The varieties of celery were tested both 
in the greenhouse and in the field. Taste I shows the relative 
TABLE I 
RELATIVE SUSCEPTIBILITY OF VARIETIES OF CELERY UNDER GREENHOUSE 
CONDITIONS* 
|Average number of spots per plant 
Vou LONGO toes : 
mura / | plants First inocu- | Second inocu- 
lation | lation 
Pe PANE Pah i ere AG ey ie | 12 5-7 170.5 
OM ORE Be Scouse kee oe oe aran: 10 8.4 167.0 
pee Sele Binhohing oreo eee 12 15.2 124.1 
Giant Pasc ed Soe eget SON SE aba ar N Sean Sela: | 12 4.0 103.0 
Inter Queens ns ie hay Oe et 12 2.4 51-4 
Golden Half Doni SF AAT (Mr Bere mb ORs CIS ME yarn Sei 1 6.1 43-7 
Peleriag i an ork eal aes II 3:2 | 23-0 
susceptibility of six of the common varieties of celery and of 
celeriac under greenhouse conditions. The plants grown in the 
greenhouse were six to eight inches high at the time of the first 
inoculation (June 26 and June 30), and were quite uniform in size 
(except the variety, Giant Pascal, which was somewhat larger). 
The plants were not in a vigorous growing condition judging from 
the yellowing of outer leaves and the slow rate of growth. It will 
be noted that the first inoculation produced comparatively low 
counts. The plants were inoculated again without repotting on 
August 27 and August 29 when conditions were more favorable 
for infection. The data as far as they go suggest that there is 
some consistent difference in varietal susceptibility, although no 
variety shows any pronounced resistance. The white varieties, 
Golden Self Blanching and White Plume, show especial sustep- 
tibility. In the field the variety test included the varieties 
Boston Market and Henderson’s Easy Blanching, in addition to 
the varieties used in the greenhouse. The estimation of damage 
done by the fungus was much less nia a in the field than in the 
However, 
among the lowest counts cilia from the infestation were those 
of the variety, White Plume, which stands highest in the wil counts. Hence it 
does not seem that the presence of the nemat 
odes materially affects the position of 
the varieties as presented here. 
