768 
that can be recommended. It is sug- 
gested that when the boards are first put 
up to the celery, under such conditions 
as accompany the heart rot, they should 
be left apart at the top and only closed 
up to the usual point after an interval 
of several days. This secures better 
ventilation and often prevents the disease. 
A. D. SELBY, 
Wooster, Ohio 
Hottow CELERY. See Bad Seed, this 
section. 
Late Blight 
Septoria petroselini var. apii 
Fr. D. BAILEY 
The disease commonly known as late 
blight of celery seems to be the most 
serious disease of that crop in Oregon. It 
is commonly found in most parts of this 
country where celery is grown. It also 
occurs in Europe, and by many is believed 
to have been introduced into this coun- 
try, probably through seed. There is a 
possibility, however, that a_ similar 
disease is present on some native weed 
of the celery family and has spread to 
the cultivated varieties of celery. 
This disease occurs in the plants in the 
form of spots on the blade of the leaf, 
though the disease may attack the leaf 
bases. The spots are small, irregular in 
- outline, and tawny in color (Fig. 1). 
These spots are caused by a_ fungus 
known as Septoria petroselini, var apii. 
If examined with a hand lens, numerous 
small black specks which are slightly 
raised may be seen scattered irregularly 
in the spots. These spots contain the re- 
productive bodies or spores of the fungus. 
These spores escape through a minute 
opening and, being scattered by wind 
and rain, cause the growth of new spots. 
The spots may appear on the first leaves 
of the seedlings in the seed bed, a fact 
which suggests the possibility that the 
disease may be carried through the seed. 
When the fungus is abundant on the 
leaves, and especially on the leaf bases, 
there is a tendency to make the stalks 
brittle, so that minute transverse cracks 
are formed which reduce the market 
value. 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
Usually the spots are clearly defined, 
but under favorable conditions for the 
development of the fungus, the entire 
leaflet may be affected, resulting in a 
complete wilting of the leaves. 
The disease may also develop serious- 
ly in storage, particularly if the storage 
houses are too warm or are poorly venti- 
lated. . 
It is probable that the disease lives 
over winter in the dead leaves that are 
left in the fields at digging time. 
Gee Tine Ste. 
Fig. 1. Leaf Spot or Late Blight of Celery. 
Remedy 
It is advisable, so far as practical, not 
to trim the plants in the field. Diseased 
plants and leaves should not be thrown 
in the compost heap if the compost is to 
be used as fertilizer for celery beds or 
fields. It is also advisable, where pos- 
sible, to practice a three or four year. rota- 
tion of crops. 
Spraying must be practiced as a pre- 
ventive. The seedlings should be spray- 
ed frequently (at least once a week), be- 
ginning when they show the first leaves. 
The plants should be sprayed in the field 
often enough to cover new foliage, and 
especially after every heavy rain. Bor- 
deaux mixture should be used in the 
4-4-50 formula. Ammoniacal copper car- 
bonate may be used for the later sprays 
