Biology Reference
In-Depth Information
Chondrostereum purpureum (formerly
Stereum purpureum
).
Silver Leaf
,
Sapwood Rot
,
common on plums and other fruit trees, sometimes
important on apples, occasional on shade and orna-
mental trees, widespread but more serious in the
Northwest. The fungus enters through wounds;
grows first in heartwood, and then kills sapwood
and bark; infected branches develop foliage with
dull leaden or metallic luster. If the disease is not
checked, the entire tree may be lost. The sporo-
phores appear after death, resupinate to somewhat
shelf-shaped, with purple undersurface.
Stereum fasciatum (Syn.
S. ostrea
).
Brown
Crumbly Rot
, mostly on slash, sometimes on
maple and birch. Thin, leathery grayish sporo-
phores with undersurface light brown, smooth.
Stereum hirsutum
Wood Rot
,
Sapwood
Wound Rot
, occasionally near wounds of living
trees -birch, maple, hickory, mountain-mahog-
any, eucalyptus, peach, and others. Thin, leathery
crustlike sporophores have hairy, buff to gray
upper surface, smooth gray undersurface.
Control
Remove branches and burn at first sign
of silvering. Protect trees from wounds; paint
pruned surface with bordeaux paste or other dis-
infectant; keep brush removed from orchard.
Stereum purpureum (see
conidia in chains on sporophores; primarily soil
forms, some parasitic.
Streptomyces ipomoea (Syn.
Actinomyces
ipomoea
)
Soil Rot or Pox
of sweet potatoes, gen-
eral New Jersey to Florida and in the Southwest.
This pathogen also infects
Jacquemontia
. Leaves
are small, pale green to yellow; plants are
dwarfed, make little or no vine growth, and may
die before end of the season; the root system is
poorly developed with most roots rotted off, or
breaking off if plant is pulled from the soil. Small
dark lesions are formed on stems below the soil
line. Pits with jagged or roughened margins, often
coalescing, are formed on mature roots. The rot is
found in soils at pH 5.2 or above; and is worse in
dry soils and seasons. Variety Porto Rico is very
susceptible.
Control
Apply sulfur to acidify soil to pH 5.0.
Stromatinia
Ascomycetes, Helotiales,
Sclerotiniaceae
Apothecia arising from a thin, black,
subcuticular, effuse sclerotium or stroma;
small black sclerotia are borne free on mycelium,
not giving rise to apothecia. There is no
conidial stage; apothecia resemble those of
Sclerotinia
.
Stromatinia gladioli (Syn.
Sclerotinia gladi-
oli
).
Dry Rot
of gladiolus, also found on crocus,
freesia and tritonia. Lesions on corms start as
reddish specks, with slightly elevated darker bor-
der; spots enlarge, and centers become sunken,
dark brown to black with lighter raised edges;
they grow together into irregular areas. On
husks the lesions are tobacco brown. Very small
black sclerotia are formed on husks, in corm
lesions, and on dead stems. Plants in the field
turn yellow and die prematurely owing to decay
of leaf sheath. Corms may appear normal when
dug, the rot developing in storage. The disease is
more prevalent in heavy soils, and the fungus can
survive several years in soil. Apothecia have been
produced artificially by fertilizing receptive bod-
ies on sclerotia with spermatia (microconidia).
Chondrostereum
purpureum
).
Silver Leaf
,
Sapwood Rot
, common
on plums and other fruit trees, sometimes important
on apples, occasional on shade and ornamental
trees, widespread but more serious in the Northwest.
Stereum sanguinolentum
Red Heart Rot
of
slash and living conifers - firs and eastern white
pine. Fruiting bodies are small, not over 2 inches
wide; upper surface is a silky pale olive buff;
lower surface “bleeds” readily when wounded,
dries to grayish brown. Sporophores are produced
in profusion on dead wood, occasionally on dead
branches of living trees.
▶
Streptomyces
Schizomycetes, Actinomycetales
Intermediate form between bacteria and
fungi. Much-branched mycelium that does
not fragment
in bacillary or coccoid forms;
