Biology Reference
In-Depth Information
White Spot of turnip, Chinese cabbage, mustard,
and other crucifers, common in the Southeast.
Cercospora althaeina Leaf Spot of hollyhock
and abutilon. Spots circular, angular or irregular,
1.5 mm, olivaceous to grayish brown, with the
dead tissue falling out. The fungus winters in old
plant parts.
Cercospora angulata Leaf Spot on philadel-
phus, currant, flowering currant, and gooseberry.
Circular to angular spots, dingy gray centers, dark
purple to nearly black margins.
Cercospora aquilegiae Columbine Leaf Spot ,
reported from Kansas, Wisconsin, Oregon. Spots
circular to elliptical, reddish brown to nearly
black; fruiting is on both sides of the leaf.
Cercospora arachidicola ( Mycosphaerella
arachidicola , Teleomorph). Peanut Early Leaf
Spot . Spots light tan aging to reddish or dark
brown with a yellow halo, often confluent. Conid-
iophores on both sides of the leaf, emerging from
stomata or breaking through epidermal cells.
Conidia colorless to pale yellow or olive, with
5 to 12 cells. Control with sulfur-copper dust.
Cercospora armoraciae Horse-Radish Leaf
Spot . Tan to dingy gray lesions with yellow-
brown margin; often slightly zonate.
Cercospora beticola Cercospora Leaf Spot of
beet, general on garden and sugar beets, also on
swiss chard, spinach. Brown flecks with reddish
purple borders become conspicuous spots with
ash-gray centers and purple margins. The brittle
central tissue often drops out, leaving ragged
holes. The spots usually remain small but are
often so numerous that foliage is killed. If suc-
cessive crops of leaves are lost, the crown of the
beet root is elongated and roughened. Leaf spot-
ting is of little direct importance except in chard,
where foliage is used for greens. The beet root
yield is reduced.
The grayish color of the spots is due to long,
thin, septate conidia produced on conidiophores
protruded through stomata in fascicles or groups,
coming from a knotted mass of mycelium resem-
bling a sclerotium. Conidia are spread by rain,
wind, tools, and insects. Infection is through sto-
mata; disease spread is most rapid under condi-
tions of high humidity that keep stomata open.
Hot weather favors the disease.
Control Crop rotation is highly important. In
a small garden pick off the first spotted leaves.
Cercospora
bougainvilleae (see
Cercosporidium bougainvilleae ). Leaf Spot
first seen in Florida in 1962 and now the most
important pathogen of this host.
Cercospora brunkii Geranium Leaf Spot ,
mostly in the South. Spots are circular, light red-
dish brown with dark brown borders, sometimes
coalescing to kill entire leaf.
Cercospora calendulae Calendula Leaf Spot .
Spots run together to blight and kill leaves; plants
may be destroyed early in the season. Spores
enter through stomata of plants more than
a month old.
Cercospora
cannabina (see
Pseudocercospora cannabina ). Leaf Curl and
Wilt on hemp.
Cercospora cannabis Leaf Spot on hemp.
Cercospora capsici Pepper Leaf Spot ,
Stem-end Rot , common in the Southeast, serious
in rainy seasons. Spots 1/7 to 1 inch in diameter are
first water-soaked then white with dark brown
margins. Leaves turn yellow and drop. The fungus
grows through the pedicel into fruit, causing a rot
of the stem end. Loss of foliage exposes the fruit to
sunscald. Spray or dust with copper.
Cercospora circumscissa ( Mycosphaerella
cerasella , Teleomorph). Leaf Spot , Shot Hole
of apricot, plum, cherry, cherry-laurel, oriental
cherry, and chokecherry. Dead spots are some-
what larger than those caused by other shot-hole
fungi, but the damage is not serious.
Cercospora citrullina Leaf Spot of water-
melon, muskmelon, and other cucurbits. Spots
are small, circular, black with grayish centers,
occurring first on leaves in center of watermelon
hills. On cucumber, muskmelon, and squash the
spots are large and ochre-gray. Defoliation of
vines causes reduction in fruit size, but the dis-
ease is not considered important. Clean up dis-
eased vines; use a 2-or 3-year rotation; spray or
dust as for bacterial wilt.
Cercospora
Mycovellosiella
concors ). Potato Leaf Spot , Leaf Blotch .
Cercospora cornicola Dogwood Leaf Spot ,in
the Gulf states, often with Septoria florida . Spots
irregular without definite borders.
concors (see
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