Biology Reference
In-Depth Information
then no more chemical the same season. Follow
through with frequent watering.
Phymatotrichum
Physalospora mutila (see
Botryosphaeria
stevensii
).
Black Rot
of apple, in the West, similar
to disease by
P. obtusa
in the East.
Physalospora obtusa
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omnivorum (see
Phymatotrichopsis omnivors
).
Texas Root Rot
,
Phymatotrichum Root Rot
,
Cotton Root Rot
.
Botryosphaeria
obtusa
).
Black Rot
of apple,
New York Apple
Tree Canker
,
Frog-Eye Leaf Spot
, general on
apple and crabapple, from Atlantic Coast to the
Great Plains; also widespread on pear, mountain-
ash, peach, quince, currant and various woody
species.
Physalospora rhodina (see
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(see
▶
▶
Physalospora
Cankers and Diebacks
.
Botryosphaeria stevensii (formerly
Physalospora mutila
).
Black Rot
of apple, in the
West, similar to disease by
P. obtusa
in the East.
Botryosphaeria obtusa (formerly
Physalospora obtusa
).
Black Rot
of apple,
New
York Apple Tree Canker
,
Frog-Eye Leaf Spot
,
general on apple and crabapple, from Atlantic
Coast to the Great Plains; also widespread on
pear, mountain-ash, peach, quince, currant and
various woody species. The fungus, in its
anamorph state (
Sphaeropsis malorum
), was
first reported as causing apple rot in 1879.
The lesions start as small brown spots, fre-
quently at a wormhole, but they darken and turn
black as they expand. There is usually one lesion
to an apple, often at the calyx end, with concen-
tric zones of black and brown, and minute black
pycnidia. The rot eventually takes in the whole
fruit, which is shriveled and wrinkled and finally
mummifies. The pycnidia are black, carbona-
ceous, and may contrain three types of
spores - large one-celled brown spores, large
hyaline spores, and two-celled colored spores.
Perithecia, sometimes formed in cankers or on
twigs, apparently play little part in the life his-
tory, the fungus wintering as dormant mycelium
or in the pycnidial state. Conidia, entering
through wounds, start primary infection in spring
on leaves with the small “frog-eye” leaf spots.
Control
Use the same spray schedule as for
apple scab, starting with the petal-fall applica-
tion. Clean up mummied apples; avoid bruising;
cut out cankers.
Botryosphaeria rhodina (formerly
Physalospora rhodina
).
Diplodia Rot
of citrus,
fig, rubber-tree and pear, possibly apple. The
conidial stage is a
Diplodia
, probably
D. natalensis
, with dark, two-celled spores.
▶
Botryosphaeria
rhodina
).
Diplodia Rot
of citrus, fig, rubber-tree
and pear, possibly apple.
Phytophthora
▶
Blights
.
Phytophthora cactorum
Stem Rot
,
Foot Rot
of
lily,
Photinia
, tulip,
Hydrastis
, blue laceflower,
baby's breath,
Centaurea
, peony, clarkia, rhu-
barb and tomato; leather rot of strawberries; col-
lar rot of dogwood, walnut, apple and pear; crown
rot of Euonymus and strawberry; root rot of box-
wood and vinca, and crown rot of peach and
Cannan fir; kernel and shuck rot of pecan. With
foot rot, lilies suddenly fall over, wilt and die; the
lower part of the stem is shrunken. Plant only
healthy bulbs and where the disease has not
occurred previously.
Strawberry leather rot occurs when berries
come in contact with soil, starting with a brown
rotted area on green fruit and a discoloration of
vascular bundles. Ripe fruit has a bitter taste.
Crown rot of rhubarb starts with slightly sunken
lesions at base of petiole, which enlarge until the
entire leaf collapses. Spraying crowns with bor-
deaux mixture is helpful. Start new beds with
healthy plants. Collar rot on English walnut is
a bark disease starting below the ground with
irregular dark brown or black cankers and soft,
spongy areas at the crown, a black fluid in cam-
bial cavities. Trees are stunted, with sparse yel-
low-green top growth. There may be an unusually
heavy crop of nuts, but the tree dies the next
season. Grow walnuts grafted on Persian or
Paradox rootstocks. See under
Cankers and
Diebacks
for symptoms on apple and dogwood.
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