Biology Reference
In-Depth Information
Septoria callistephi
Leaf Spot
,
Damping-off
,
Stem Rot
of China aster.
Septoria chrysanthemella and S. obesa -
Chrysanthemum Leaf Spot
, also on oxeye
daisy, general through eastern and central states
to Florida; also reported in the West. This disease
is sometimes confused with nematode injury, but
the leaf nematode browns the leaves in wedge-
shaped areas between veins, and the fungi cause
definite spots. These are first small and yellowish,
then dark brown to nearly black. Sometimes the
spots coalesce into blotches; minute black
fruiting bodies are faintly visible. Leaves may
turn yellow and drop prematurely or dry and
hang down along the stems. Spores are splashed
from plant to plant in watering or rain, and are
spread on cultivating tools.
Control
Avoid syringing greenhouse plants; do
not cultivate outdoor plants, when they are wet.
Septoria citri
Citrus Septoria Spot
on leaves but
more serious on fruits. Small, shallow, light brown
depressions on green immature fruit retain a green
marginal ring as the fruit colors. Usually a minor
trouble, sometimes important in California.
Septoria citrulli
Watermelon Leaf Spot
. The
pathogen is like
S. cucurbitacearum
except that
spores are shorter.
Dogwood Leaf Spot
.
Septoria cornicola Angular lesions between
veins are grayish with dark purple margins.
Septoria cucurbitacearum
Septoria Leaf Spot
of cucurbits, on cucumber, winter squash, musk-
melon, and watermelon. Foliage spots are small,
gray, circular, rather conspicuous, often bordered
with a zone of yellow tissue. The fungus fruits
abundantly on upper side of leaves, with long thin
septate spores in black pycnidia. It winters in old
plant parts; clean up all refuse at end of the season.
Septoria cyclaminis
Leaf Spot
on cyclamen.
Septoria dianthi
Septoria Leaf Spot
of Dian-
thus, on carnation and sweet william. Spots are
more or less circular, light brown with purplish
brown borders, scattered over leaves and stems,
particularly on lower leaves. The spots may
enlarge, and the leaves die. Take cuttings from
disease-free plants; avoid syringing, or do it early
in the day.
Septoria divaricatae (see
Septogloeum
Deuteromycetes, Coelomycetes
Acervuli subepidermal, erumpent, pale; conidio-
phores short, simple; conidia hyaline, several-
celled, oblong to fusoid; parasitic.
Diplodia acerina (formerly S
eptogloeum
acerinum
).
Maple Leaf Spot
. A small leaf spot
occasionally defoliating Norway and Schwedler
maples in the Middle West.
Cheilaria agrostis (formerly
Septogloeum
oxysporum
).
Char Spot
of lawn grasses. Lesions
are tawny with yellow margins, circular becom-
ing elliptical, pointed at each end, covered with
dull black to brown stromatic tissue.
Septogloeum
Diplodia
acerinum (see
▶
acerina
).
Maple Leaf Spot
.
Septogloeum oxysporum (see
Cheilaria
▶
agrostis
).
Char Spot
of lawn grasses.
Septogloeum parasiticum
Elm Leaf Spot
,
Twig
Blight
.
Septogloeum rhopaloideum (
Guignardia
populi
). Grayish brown, circular or irregular
spots on poplar.
Septoria
Blights
.
Septoria agropyrina
Brown Leaf Blotch
on
wheatgrasses.
Septoria bataticola
Sweet Potato Leaf Spot
,
occasional, most common in northern tier of
sweet potato states. Minute white spots on leaves
are bordered with a narrow reddish zone. Older
lesions have one or more pycnidia barely visible
to the naked eye. The spores, oozing out in ten-
drils when water is present on the leaf, are spread
by rain and insects. No control is needed except
cleaning up crop refuse.
Septoria calamagrostidis
Leaf Spot
on bent
grasses. Scattered gray to straw-colored lesions
at tip of blades, appearing in Northwest in late
winter and early spring. Seaside creeping bent is
especially susceptible.
▶
Septoria phlogis
).
▶
Septoria Leaf Spot
of phlox.
