Biology Reference
In-Depth Information
Indiana, Missouri, North and South Carolina and
Ohio. Serious in cool rainy weather, causing pre-
and post-emergence damping-off.
Phytophthora syringae
Root Rot
on shore juni-
per and Photinia.
Phytophthora
Pleospora herbarum
Fruit Rot
of tomato.
A firm dark rot develops in fruit after picking,
starting from infections through cracks near stem
end of fruit. Progress is most rapid at 65
to 70
F
and is checked by storage at 45
F.
torulosum
Root
Rot
and
Damping-off
on soybean.
Pleurotus
Plectospira
Basidiomycetes, Agaricales
Oomycetes, Saprolegniales
Stipe off center or lacking; cap sometimes
inverted; gills more or less fleshy and separable
into two layers, edges acute; spores white.
Hypsizygus ulmarius (formerly
Pleurotus
ulmarius
).
Brown Heart Rot
sapwood wound rot
of elm, maple, and other living hardwoods. Rot
starting in heartwood may extend into sapwood;
infected wood separates along annual rings.
Annual sporophores have a long excentric stalk,
and white to yellow to brown smooth upper sur-
face. They issue from crotches and pruning
wounds.
Pleurotus ostreatus, oyster cap.
White Flaky
Sapwood Rot
of maple and other hardwoods,
sometimes on living trees. A light-colored decay
is surrounded by a narrow brown zone. Fleshy
annual conks are shelving, sessile, or with a short,
stout excentric stalk. The upper surface is
smooth, white or grayish, gills extending onto
the stalk, an edible fungus. Infection is through
open wounds.
Wood Rot
of grape.
Pleurotus
Sporangium with much inflated branching;
swarm spores are formed in basal portion and
cut out into a single row in an elongate filamen-
tous apical portion, which acts as an exit tube.
Swarm spores encyst at the mouth as in
Aphanomyces
. Oogonium terminal or intercalary,
accompanied by up to 65 antheridia.
Plectospira myriandra
Rootlet Necrosis
on
tomato. The fungus is weakly parasitic on roots.
Plenodomus
Deuteromycetes, Coelomycetes
Pycnidia coriaceous or carbonaceous, more or
less sclerotoid. Condiophores obsolete or none;
conidia one-celled, hyaline.
Plenodomus destruens
Foot Rot
of sweet
potato, one of the more important field diseases
and sometimes a storage rot. The base of the stem
turns brown from just under the soil surface to 4
or 5 inches above; leaves turn yellow and drop
off; vines wilt unless adventitious roots are put
out; pycnidia are numerous. The root has a firm
brown rot, not affecting the whole potato but
enough to make it worthless for food. The fungus
winters in old plant refuse but not in soil. Use
clean seed potatoes; rotate crops. This fungus
also infects
Jacquemontia
.
Hypsizygus
ulmarius
).
Brown Heart Rot
sapwood wound rot
of elm, maple, and other living hardwoods.
ulmarius (see
▶
Polyporus
Basidiomycetes, Aphyllophorales
Pileus tough, thick, with a stipe, or as a shelf;
pores rounded, small, tubes crowded.
Dichomitus squalens (formerly
Polyporus
anceps
).
Red Ray Rot
on western conifers, caus-
ing heart rot of living trees but beneficial as
a cause of rapid decay of slash in forests. Fruiting
bodies rarely develop on living trees.
Pleospora
Leaf Spots
.
▶
