Biology Reference
In-Depth Information
into flower, the ascospores infecting the perianth
and causing flower spotting. From withered
flowers numerous large conidia, germinating
with several germ tubes, infect foliage, on
which large sclerotia are formed late in the sea-
son. Remove infected parts immediately; spray
early in the season.
Ciberinia camelliae (formerly
Sclerotinia
camelliae
).
Camellia Flower Blight
, long known
in Japan, first noted in California in 1938, con-
firmed in Georgia in 1948, although probably
there several years previously, reported in Ore-
gon in 1949, Louisiana and North Carolina in
1950, South Carolina in 1954. The blight is now
widespread in Virginia, confined to certain
counties in other states. It was not officially
recorded from Texas until 1957 but must have
been there earlier. The 1950 outbreak at Shreve-
port, Louisiana, is said to have started on plants
brought in from Texas that probably originated in
California.
Floral parts only are affected, infection taking
place any time after tips of petals are visible in
opening buds. Few to many brownish specks on
expanding petals enlarge until the whole flower
turns brown and drops. In early stages darkened
veins are prominent diagnostic symptoms. When
the flowers rest on moist earth, spermatia are
produced on petals in shiny black masses. Hard,
dark brown to black sclerotia formed at the base
of petals frequently unite into a compound struc-
ture simulating petal arrangement. This com-
pound sclerotium may be an inch or more in
diameter. Although the petals do not melt when
touched as do azaleas with petal blight, there is
a distinctive moist feeling that helps to differen-
tiate flower blight from frost injury. Rarely,
a flower blight of camellias is caused by another
Sclerotinia
(
S. sclerotiorum
).
Sclerotia lie dormant on ground or in
mulching materials until the next winter when,
from January on (possibly earlier), after wet
periods with rising temperature, they produce
one to several apothecia on long or short stipes
with brown, saucerlike discs 1/4 to 3/4 inch
across, rarely up to 1 inch. Spores, discharged
forcibly, are carried by wind currents to flowers,
thus completing the cycle. Spores may be
Schirrhia
Ascomycetes, Dothideales,
Dothideaceae
Asci usually short, cylindrical, and relatively
numerous in spherical, ostiolate locules.
Scleropycnium
Deuteromycetes, Coelomycetes
Pycnidia open out to a deep cupulate or discoid
structure, tough, dark or black, subepidermal or
subcortical, then erumpent; spores hyaline, one-
celled. Largely saprophytic on twigs, sometimes
parasitic on leaves.
Scleropycnium aureum
Leaf
Blight
of
mesquite.
Sclerotinia (Whetzelinia)
Ascomycetes, Helotiales,
Sclerotiniaceae
Apothecia arising from a tuberoid sclerotium
which, though formed free on aerial mycelium,
is sometimes enclosed in natural cavities of
suscept or host, as in hollow stem of perennials.
Interior (medulla) of sclerotium white,
completely enveloped by a dark rind; gelatinous
matrix lacking. Conidia wanting but spermatia
(very small microconidia) formed on
sporodochia borne free or enclosed in cavities.
Apothecia some shade of brown; cupulate to fun-
nel-form; usually at maturity saucer-shaped to
flat expanded; ascospores hyaline, one-celled,
ovoid. Species formerly included in
Sclerotinia
but possessing monilioid conidia are now in
Monilinia
.
Botryotinia polyblastis (formerly
Sclerotinia
polyblastis
).
Narcissus Fire
. A serious flower
blight in England, known here on the Pacific
Coast. In England overwintering sclerotia pro-
duce apothecia when
Narcissus tazetta
comes
