Biology Reference
In-Depth Information
Sooty Mold
Sooty mold is a black coating on surface of leaves
or fruit composed of a weft of dark mycelial
threads. As here used, the term applies to sapro-
phytic fungi that live on insect honeydew and
harm plants only indirectly. See
stylospores in very long flask-shaped concepta-
cles,
and muriform brown
ascospores
in
perithecia.
Although sooty molds do not obtain food from
the plant, the black membrane interferes greatly
with photosynthesis and food manufacture.
Affected fruit is smaller, with coloring retarded;
it is more likely to decay than normal fruit.
Control
is directed against the insects, either
by spraying with insecticides or by using
entomogenous fungi and insect parasites. Oil
sprays kill the insects and help to clean the trees
of the sooty covering.
Capnodium elongatum
Sooty Mold
of tulip-
tree, oleander, holly-osmanthus, and others.
Foliage of tulip-trees very frequently has
a black coating, often on honeydew secreted by
the tulip-tree aphid, sometimes following attacks
of tulip-tree scale. A dormant oil spray controls
the latter.
Capnodium spp
Sooty Mold
on gardenia, fig,
crape-myrtle, azaleas, and many other plants.
Gardenias are especially subject to sooty mold
following whiteflies, crape-myrtle after aphids,
azaleas after mealybugs and magnolias after
scales. A summer oil spray helps to control the
insects and loosens the black coating so that it is
more readily washed off.
Very often rhododendronss and other broad-
leaved evergreens growing inside the branch
spread of tulip and other trees afflicted with
aphids and scales are covered with sooty mold
growing in the honeydew dropped down on
foliage from the tree overhead.
Black Mildew
for the true parasites with dark mycelium and
spores giving a sooty appearance to foliage.
▶
Capnodium
Ascomycetes, Capnodiales
Mycelium superficial, dark; spores muriform, in
perithecium-like conceptacles at tips of branches
of a carbonaceous stroma; associated with insect
secretion on living plants.
Capnodium citri
Sooty Mold
on citrus, on hon-
eydew secreted by scale insects, aphids, white-
flies, especially abundant following whiteflies in
Florida, black scale in California. A black velvety
membranous coating is formed over leaves,
twigs, and fruit. If honeydew is slight, the coating
appears in spots; but if the insect secretion is
abundant, the entire surface may be covered by
a dense continuous membrane resembling black
tissue paper. With age, under dry conditions it
may be blown off in fragments. The black mem-
brane is made up of hyphae that are individually
olive green to deep brown, with wide short cells.
Branches may crisscross or be cemented
together. There are several spore forms: simple
conidia that are cut off from upright hyphae,
others
formed
in
small,
black
pycnidia,
