386 OHIO EXPERIMENT STATION: BULLETIN 214 
The decayed parts are teeming with motile bacteria to which this form of decay 
has been attributed. The heart-rot prevails tooin very hot, steamy weather, 
but preventive measures are about all that can be recommended. It is suggested 
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 ventila- 
tion and often prevents the disease. 
Root-Rot. During a succession of wet seasons much trouble developed in 
the Akron district from attacks of root-rot (Rhizoctonia). This gave trouble at 
times with the seedling plants, but more seriously with the shortened develop- 
ment of the crop. Often the roots were nearly all rotted off. Thetrouble seemed 
to decline rapidly with drier seasons. (See Circular No. 72, Ohio Exp. Sta.). 
Rust, true and false. In Europe the celery plant is attacked by one or two 
rust fungi (Puccinia bullata (Pers.) and P. Castagnéi Thim.) of the same class 
of parasitic fungi as those producing rust in wheat. These two rusts have not 
as yet been discovered in America, though they will doubtless in time become 
introduced. Celery which is banked in the earth often has the blanched stems 
marked by rusty spots of various sizes. These spots appear to arise from the 
contact of the stems with the earth, and on microscopic examination seem to be 
due to the fungi or bacteria, or both, that may be present in the soil. The 
difficulty is prevented by avoiding this method of blanching and substituting 
boards or close culture planting. : 
Bad Seed. There is scarcely’a more vital question in celery growing than 
that of the quality of seed used. Seed that is of a bad strain though true to 
varietal name, may inflict losses of hundreds or thousands of dollars on large 
growers. Hollow celery, or that otherwise useless, according to present know- 
ledge is very often due to the bad seed. 
CHERRY 
Black-Knot. This is a conspicusus disease attacking 
the branches of cherry and plum trees but is more frequent 
upon the cherry varieties of the Morello type. It is due to 
a parasitic fungus (Plowrightia morbosa Schw.). Insects, 
however, make harbors of the interior of the knots. The 
spores of the black-knot fungus are ripened during the 
winter and scattered in early spring, finding lodgement on 
the new branches or in fractures on old ones, where their 
growth causes the formation of anew knot. Black-knot 
may be prevented by spraying with Bordeaux mixture, but 
is more profitably controlled by carefully cutting off 
affected parts and burning them, making a clean sweep at 
least once each year and that previous to March rst. This 
is a practicable measure and we have confidence in its 
efficiency. 
Leaf-Spot and Mildew. The first named disease is 
Fig. 40. Twig of caused by the same fungus (Cylindrosporium Padi Karst.) 
cherry attacked by as that which we call ‘‘shot-hole fungus’’ on the plum, and 
black knot. This is the 
summer condition May be successfully prevented by the use of Bordeaux mix- 
wen ne ear ore ture, except that only half the strength of mixture may be 
surface and often give applied with safety to the foliage of the cherry. (See Cal- 
inate ‘a ea a endar). The mildew is usually found chiefly upon sprouts 
