Biology Reference
In-Depth Information
Calonectria colhounii
Leaf Spot
on sentry palm.
Calonectria crotalariae
Leaf Spot
on sentry
palm.
Calonectria theae
Leaf Spot
on sentry palm.
Cephalosporium
Deuteromycetes, Hyphomycetes
Conidiophores slender or swollen, simple;
conidia hyaline, one-celled, produced succes-
sively at the tip and collecting in a slime drop,
produced endogenously in some species; sapro-
phytic or parasitic, some species causing vascular
wilts of trees.
Cephalosporium apii
Celery Brown Spot
,
a new disease first reported from Colorado in
1943, later from New York and Ohio. Irregular
light tan or reddish brown shallow lesions are
formed on celery leaf stalks, petioles, and leaflets.
They may unite to make a scurfy brown streak up
the inside of the stalk and may develop transverse
cracks. Utah and Pascal varieties are most
susceptible.
Cephalosporium cinnamomeum
Leaf Spot
of
nephthytis and syngonium. Small circular to
irregular spots, reddish brown with pale yellow
borders enlarge, with centers becoming gray and
papery. In severe cases leaves turn yellow and
die. Pick off infected leaves. Maintain low tem-
perature and humidity.
Cephalosporium dieffenbachiae
Dief-
fenbachia Leaf Spot
. Small red lesions with
dark borders appear on young leaves. Spots
sometimes run together, and the whole leaf
turns yellow and dies. Infection is often through
mealybug wounds. Avoid promiscuous syring-
ing; keep temperature and humidity low; control
mealybugs, and ants that transport them.
Cephaleuros
One of the green algae, possessing chlorophyll
but not differentiated into root, stem, and leaves;
forming motile spores in sporangia.
Cephaleuros virescens
Algal Spot
,
Red Leaf
Spot
,
Green Scurf
in the far South or in green-
houses on acacia, albizzia, ardisia, avocado, bixa,
bischofia, camellia, camphor-tree, cinnamon-
tree, citrus, grevillea, guava, jasmine, jujube,
loquat, magnolia, mango, pecan, Japanese per-
simmon, privet, rhododendron, viburnum.
On some hosts this is a disease of twigs and
branches, which may be girdled and stunted, cov-
ered with reddish brown hairlike fruiting bodies.
On magnolia leaves velvety, reddish brown to
orange, cushiony patches are formed, but in the
absence of sporangia (tiny globular heads on fine,
dense reddish hairs) the leaf spots remain green-
ish brown. Occasionally citrus fruits as well as
leaves are attacked.
The sporangia formed on the fine hairs germi-
nate in moist weather, producing zoospores that
enter through stomata and form mycelium-like
chains of algal cells in host tissue. On twigs the
alga invades outer cortical tissue, which may
swell abnormally, crack, and afford entrance to
injurious fungi. Weakened trees are most suscep-
tible, and disease spread is most rapid in periods
of frequent and abundant rains. Twigs may die,
and there may be reduced yield of citrus fruit.
Control
Improve draining and other growing
conditions; citrus trees sprayed regularly with
copper seldom have algal trouble. If it gets
started, follow cleanup pruning with a bordeaux
mixture spray in December or January. Repeat
with bordeaux at start of rainy season or when red
stage of the alga is first seen, and spray again
1 month later. A neutral copper may substitute
for bordeaux for the last two applications. The
copper kills beneficial insects parasitic on scales,
but the oil controls the scale insects.
Cercospora
▶
Blights
.
Cercospora abeliae
Abelia Leaf Spot
, reported
from Louisiana. Irregular purple to brown spots;
defoliation.
Cercospora
abelmoschi (see
Pseudocercospora abelmoschi
).
Leaf Spot
on
okra, hibiscus.
Cercospora albo-maculans (Syn. Cercosporella
brassicae)
▶
(see
Pseudocercospora capsellae
).
▶
