Biology Reference
In-Depth Information
They are densely crowded, 3 to 7 mm broad, on
stipes 6 to l0 mm high.
Control
Use soil with good drainage and
a 4-year rotation. Removing husks before plant-
ing helps to reduce gladiolus rot diseases. Cure
corms rapidly after harvest.
Stromatinia narcissi Large-scale speck fungus
on narcissus and zephyranthes. Black, thin,
round, flat sclerotia 1/2 to 1 mm, adhere firmly
to outer scales. The fungus is mostly on bicolor
varieties and seems to be saprophytic without
causing a definite disease.
Control
Sterilize soil for seedbeds; use clean
pots for poinsettias and other greenhouse plants;
reduce pH with sulfur or by using half peat moss
and half soil.
Trametes
Basidiomycetes, Aphyllophorales
Pileus without stipe, sessile to effuse-reflexed,
firm; hymenium white or pallid, punky to corky,
not friable when dry; tubes unequally sunken.
Trametes suaveolens
White Wood Rot
of wil-
low and poplar, after wounding. A dry, corky
decay with an anise odor begins in lower trunk
and progresses upward. Leathery to corky sporo-
phores 6 inches wide are white when young, gray
to yellow with age.
Thielaviopsis
Deuteromycetes, Hyphomycetes
Hyphae dark; two kinds of conidia-small, cylin-
drical, hyaline endogenous spores and large,
ovate, dark brown exogenous
spores, both
Trichoderma
formed in chains.
Thielaviopsis basicola
Black Root Rot
, seedling
root rot of tobacco and many vegetables - bean,
carrot, corn, chickpea, lentil, okra, onion, pea,
tomato, corn-salad, vinca, and watermelon; and
ornamentals - begonia, cyclamen, gerbera, elm,
oxalis, lupine, pelargonium, peony, poinsettia,
pansy, scindapsus, and others. There is blacken-
ing and decay of roots; young plants damp-off
and die; older plants are stunted, with the decay
proceeding until all roots are destroyed. Stem
discoloration extends 2 to 3 inches above the
soil line. The fungus lives in soil as
a saprophyte, entering through nematode
wounds. Hyaline conidia produced inside
conidioles are forced out through hyphal tips.
Chlamydospores are larger, dark, club-shaped,
with several cells; they break up so that each
pillbox acts as a spore. This disease is especially
serious on poinsettia, dwarfing plants, causing
misshapen leaves and flower bracts. The rot is
most destructive in heavy, cold, slightly acid to
alkaline soils well supplied with humus. Long
wet periods after transplanting increase rot.
Soils with pH lower than 5.6 or sandy soils low
in organic matter are less conducive to disease.
Deuteromycetes, Hyphomycetes
Conidia in heads on conidiophores divided into
two or three tips, a single head on each tip; spores
hyaline, one-celled.
Trichoderma viride
Green Mold Rot, Cosmo-
politan
on narcissus, also on shallot, garlic, occa-
sional on citrus, but saprophytic. This fungus has
an antibiotic or antagonistic effect on
Rhizocto-
nia, Pythium
, and other damping-off fungi and is
quite helpful in reducing Armillaria root rot and
crown rot due to
Sclerotium rolfsii
.
Trichoderma harzianum
Fruit Rot
of apples in
storage.
Trichothecium
Deuteromycetes, Hyphomycetes
Conidiophores long, unbranched; conidia two-
celled, hyaline or bright, single, at apex of conid-
iophore; upper cell usually larger than basal cell;
mostly saprophytic.
