Biology Reference
In-Depth Information
Septoria gladioli
Leaf Spot
. More important as
a hard rot of gladiolus corms.
Septoria glycines
Brown Spot
of soybean. Pri-
marily a foliage disease, this may also appear on
stems and pods. It starts with irregular brown
patches on cotyledons, then reddish brown zones
on both sides of leaves, often with pale green or
chlorotic zones surrounding the lesions. Spots may
cover the whole leaf, defoliation starting from low-
est leaves. Brown discolorations with indistinct
margins extend an inch or more along stems. The
pathogen winters in diseased leaves and in seed.
Some varieties are quite resistant. Use healthy
seed; treatment is unsatisfactory; rotate crops.
Septoria lactucae
Septoria Leaf Spot
of lettuce,
occasionally destructive to some varieties.
Lesions are more common on lower leaves -
irregular reddish marks, dotted sparsely with
black pycnidia. The fungus is disseminated with
seed.
Septoria loligena
Leaf Spot
on ryegrass, in
California. Chocolate brown spots, paler in the
center, surrounded by lighter areas.
Septoria lycopersici
Septoria Leaf Spot
of
tomato,
Leaf Blight
, quite destructive in Atlantic
and central states, less important in the South and
West. In seasons with moderate temperature
and abundant rainfall enough foliage is destroyed
so that fruits do not mature properly and are sub-
ject to sunscald. The disease appears at any age but
more often after fruit is set. Infection starts on
older leaves near the ground, with small, thickly
scattered, water-soaked spots, which become
roughly circular with gray centers and prominent
dark margins. The spots are smaller, 1/16 to 1/8
inch, and more numerous than those of early
blight. Leaflets may die with progressive loss of
foliage from the bottom up. The pathogen winters
on tomato refuse and solanaceous weed hosts;
spores are washed from pycnidia by rain or spread
by brushing against moist leaves. Optimum tem-
perature is 60
to 80
F.
Control
Bury plant remains deep in soil or burn;
control weeds; use long rotations.
Septoria oudemansii
Leaf Spot
of bluegrass, in
northern states. Dark brown, purple spots turning
straw-colored appear on leaf sheaths and spread
to blades, with turf turning yellowish brown.
Plants may be defoliated in cold wet seasons,
but they are rarely killed.
Septoria paeoniae
Septoria Leaf Spot
of peony,
Stem Canker
. Round gray spots with reddish
borders are found on stems and leaves. Control
with sanitary measures.
Septoria phlogis (formerly
Septoria
divaricatae
).
Septoria Leaf Spot
of phlox. Dark
brown circular spots, up to 1/4 inch in diameter,
have light gray to white centers and often run
together in blotches.
Septoria pistaciarum
Leaf Spot
on pistachio.
Septoria populicola
Leaf Spot
of poplar.
Septoria rubi (Teleomorph,
Mycosphaerella
rubi
).
Blackberry Leaf Spot
on blackberry, and
dewberry, perhaps with more than one strain. See
▶
Sphaerulina rubi
for forms reported on red
raspberry. Leaf spots are light brown, sometimes
with a purple border. Infection is usually so late in
the season that it is of minor importance, but it
may cause some defoliation.
Septoria secalis var. stipae
Leaf Spot
on bent
grass. White spots turn straw-colored, with
scattered pycnidia.
Septoria
spraguei
Leaf
Spot
on Russian
wildrye (
Elysum
).
Septoria tageticola
Marigold Leaf Spot
,
reported in 1958 from Florida. Spots are oval to
irregular, smoky gray to black, speckled with
minute black pycnidia. The disease advances
upward from the lower leaves and also infects
younger branches, peduncles, bracts, and seed.
African marigolds are very susceptible, French
almost immune.
Septoria tenella
Leaf Spot
on fescue grasses.
Small, vague, greasy brown spots.
Septoria tritici var. lolicola
Leaf Spot
on
ryegrass. Indefinite green to yellow mottled or
blotched spots becoming fuscous to deep brown.
Sphaerulina
Ascomycetes, Dothideales
Perithecia separate, innate to erumpent, not
beaked, lacking paraphyses and paraphysoids;
hyaline, with several cells; clavate-cylindrical.
