124 PICTORIAL PRACTICAL CARNATION GROWING. 
commenced as soon as the first trace of the mildew is noticed. The 
application may be at short intervals until the Oidium is completely 
eradicated. 
II.—Rust. 
Carnation rust or brand produces at first pale spots on the leaves 
and stems, followed by scattered, minute, elevated blisters, which 
are for a long time covered by the cuticle. These particles crack at 
the apex, and disclose the powdery chocolate or orange coloured 
spores. The first spores are uredospores, spheroid or elliptical, and 
rather large, externally rough, and pale brown, chocolate or orange 
in colour. No aecidia spores or cluster cups are associated with the 
uredospores. 
The teleutospores or resting spores are the last to arrive ; they are 
globose, rarely oblong, with the cell membrane thickened at the apex, 
and a little narrowed below into the long, deciduous pedicel ; they 
are brown, becoming darker with age, one celled, and smooth. 
The fungus grows wholly within the leaf or stem of the Carnation, 
which it distorts, ultimately bursting the cuticle on both sides for 
the emission of the spores. These—uredospores—are produced in 
great numbers, and are scattered far and wide. They quickly ger- 
minate upon Carnation leaves, and push germ tubes, that quickly 
gain access to the interior of the leaves by the stomata and then 
form new pustules. This process is repeated till in bad cases all the 
foliage and sometimes the stem is involved in the disease. 
The resting spores hibernate for a time, or through the winter, 
in dead Carnation refuse, and germinate in this decaying material 
in or on the ground in the spring, at which time they make their 
attack on previously unaffected Carnations. In greenhouses the 
fungus grows continuously all through the winter by its uredospores ; 
it frequently produces resting spores in the same pustules with the 
uredospores. 
Carnation rust is usually confined to plants grown under glass, 
the fungus apparently being powerless to attack plants outdoors. 
Plants with exceptionally blue foliage generally resist its attacks. 
FUNGOID ENEMIES. FIG. 60 (NEXT PAGE).—RUST. 
EK, a plant in a 5-inch pot infested with rust: 7, pustules on the leaves; m, 
pustules on the stem. F 
F, a deformed leaf showing: x, blisters or pustules, natural size. 
G, a fragment of a Carnation leaf showing the pustules in section: 0, leaf 
tissue ; p, raised and broken cuticle ; 7, spores (uredo) in situ, magnified. 
H, a bit of a pustule in the uredospore stage: 7, mycelium; s, pedicel; ¢, 
spore (uredo, sometimes called Uredo Diantii)—it is chocolate or orange 
in colour, and covered with minute spines ; v, a dropped spore which has 
germinated, magnified. 
I, a portion of pustule in the final stage (teleutospore) sometimes referred to 
as brand, Uromyces Dianthi, syn. U. caryophyllinus: v, mycelium; w, 
pedicel; x, teleutospore, brown in colour, turniag darker; y, smooth. 
