Biology Reference
In-Depth Information
Sphaerulina rubi (Anamorph,
Cylindrosporium rubi
).
Raspberry Leaf Spot
on
red and black raspberry only, common east of the
Rocky Mountains. This disease and a similar one
on blackberry and dewberry were for many years
considered due to
Septoria rubi
and then attrib-
uted to
Mycosphaerella
as the teleomorph state.
Later it was shown that two species were
involved, with
Sphaerulina
the ascomycete on
raspberry,
Septoria rubi
the pathogen commonly
found on blackberry and dewberry.
Spots are small, circular to angular, first
greenish black, then grayish; pycnidia produce
elongate, three-to nine-septate spores. Perithecia,
formed in fallen leaves, are black, subepidermal,
later erumpent; ascospores are cylindrical,
curved, pointed at both ends, usually four septate.
more severely when grown near very susceptible
Stoplight and Casablanca. The disease, starting
on particularly susceptible varieties, spreads radi-
ally to less susceptible plants, decreasing in
severity with distance from focal point. The leaf
spot disappears in summer and autumn, reappears
in winter 3 weeks after a cold period.
Control
Use resistant varieties to separate very
susceptible types from those partly susceptible.
Stemphylium bolickii
Leaf Spot
of echeveria,
kalancho¨, and sedum. On some species lesions
are small, raised, irregular to circular, brown to
purplish black. On other species spots are larger,
with tan centers, purplish margins.
Stemphylium botryosum (Teleomorph,
Pleospora herbarum
).
Leaf Spot
,
Black Seed
Rot
,
Seed Mold
on kidney beans, pea, onion, gar-
lic, shallot, salsify, asparagus, pepper, and tomato.
Stemphylium callistephi
Leaf Spot
of China
aster. Brown, nearly circular, concentrically
zonate spots with dark margins on leaves, bracts,
petals, and stems.
Stemphylium cucurbitacearum
Leaf Spot
of
cucurbits, on cucumbers, muskmelon, and winter
and summer squash. The pathogen is possibly
secondary, perhaps confused with
S. botryosum
.
Small brown spots with lighter centers have
mycelium growing over the lesion, producing
globose, multiseptate spores.
Stemphylium lycopersici
Tomato Leaf Spot
.
Similar to gray leaf spot but the conidia and
conidiophores longer.
Stemphylium solani
Gray Leaf Spot
,
Stemphylium Leaf Spot
in pepper, tomato,
groundcherry, eggplant, and other
Solanum
spe-
cies, mostly in the South, occasionally a problem
elsewhere. In warm, humid weather, plants are
defoliated in seedbed or field. First infection is on
older leaves, which exhibit numerous small, dark
brown spots extending through to the undersurface.
Centers are often a glazed gray-brown with crack-
ing and tearing. Leaves turn yellow and wither; all
leaves may be killed except those at the top; seed-
beds are often destroyed.
Control
Use clean soil for seedbed; spray seed-
lings at weekly intervals.
Stemphylium vesicarium,
Purple Spot
of
asparagus.
Sporonema
Deuteromycetes, Coelomycetes
Pycnidia dark, membranous or carbonaceous,
innate, opening with torn lobes; spores hyaline,
one-celled.
Sporonema camelliae
Camellia Leaf Spot
.
Stemphylium
Deuteromycetes, Hyphomycetes
Conidiophores dark, mostly simple, bearing a sin-
gle terminal conidium or successive conidia on
new growing tips; conidia dark, muriform, smooth
or spiny; parasitic or saprophytic (see
Fig. 2
).
Stemphylium sp. sp. (Teleomorph,
Pleospora
herbarum
).
Red Leaf Spot
of gladiolus, widely
distributed, causing an annual loss in Florida
since 1938. Spots are small, round, translucent,
pale yellow with reddish brown centers. Leaves
may be killed before flowering or after spikes are
cut, resulting in smaller corms. Infection takes
place with 10 h of dew or fog; rain is unnecessary;
optimum temperature is 75
F. Leaves may be
killed within 2 weeks of inoculation. Picardy
variety is moderately susceptible; it is damaged
