Biology Reference
In-Depth Information
a week in warm rainy weather, and the
fungus can survive in the soil for 3 years.
Many gladiolus varieties are more or less
resistant; Picardy and some others are very
susceptible.
Curvularia
Deuteromycetes, Hyphomycetes
Conidiophores brown, simple or sometimes
branched, bearing conidia successively on new
growing tips; conidia dark, three-to five-celled,
with end cells lighter, more or less fusiform,
typically bent or curved with central cells
enlarged; parasitic or saprophytic.
Curvularia cymbopogonis
Blight
and
Leaf
Spot
of itchgrass. Leafspots coalesce after 3 or
4 days to form larger lesions and final blighting
symptoms.
Curvularia lunata (
C. trifolii
f. sp.
gladioli
).
Gladiolus Flower Blight
and
Leaf Spot
,
Curvularia Disease
. Suddenly, in 1947, a blight
showed up in Florida as a serious threat to the
gladiolus cut-flower industry, ruining hundreds
of acres there and in Alabama in the next few
months. The disease is now recorded as far north
as New York and Wisconsin and on the Pacific
Coast. The pathogen is usually identified as
Curvularia lunata
, known as a crop pest for
many years, especially in the tropics, but studies
indicate it is a special form of
C. trifolii
, cause of
a leaf spot of clover.
Curvularia spots on leaf or stem are oval, tan
to dark brown, showing on both sides of the leaf,
bordered with a brown ring, slightly depressed
and with a narrow yellowish region between the
spot and normal green of the leaf. Tan centers of
spots are covered with black spores resembling
powder. Premature death comes when stems of
young plants are girdled; florets fail to open when
petioles are girdled.
Under favorable weather conditions tan spots
on petals turn into a smudgy flower blight.
Brown to black irregular lesions appear on
corms of blooming stock and develop further in
storage; the fungus survives in corms from one
season to the next. This is a high temperature
fungus, with optimum for growth 75
to 85
F
and no infection under 55
F. A 13-h dew period
is sufficient moisture. Leaf spots show up in 4 to
5 days, spots on florets and stems in only 2 to
3 days. The complete life cycle is as short as
Cylindrocladium
Deuteromycetes, Hyphomycetes
Conidiophores dichotomously branched; spores
hyaline, two-or several-celled.
Cylindrocladium clavatum
Blight
on bird-of-
paradise.
Cylindrocladium scoparium
Cylindrocladium
Blight
. Damping-off of seedlings and
cuttings - conifers, azalea, magnolia, hydrangea,
holly, pyracantha, bottle brush, and poinsettia -in
greenhouses under very moist conditions.
Infected azalea leaves turn black, with petiole
bases softened, and drop in a few days; the bark
turns brown. Leaves and stems are covered with
brownish mycelial strands and white powdery
masses of conidia. Control by proper humidity
and aeration.
Cylindrocladium avesiculatum
Blight
and
Leaf Spot
of
Leucothoe¨ axillaris
.
Cylindrosporium
Deuteromycetes, Coelomycetes
Acervuli subepidermal, white or pale, discoid or
spread out; conidiophores short, simple; conidia
hyaline, filiform, straight or curved, one-celled or
becoming septate; parasitic on leaves. Many spe-
cies
have
Higginsia
or
Coccomyces
as
a teleomorph state.
Cylindrosporium defoliatum
Leaf Blight
of
Hackberry. May cause defoliation but usually
unimportant.
Cylindrosporium
griseum On
western
soapberry.
Cylindrosporium juglandis On walnut.
