Biology Reference
In-Depth Information
red, chestnut, and other oaks. Shade and orna-
mental trees of all ages may be killed. Infection
may start anywhere through wounds but more
often on small twigs and branches, passing to
larger branches and trunk. Twigs and branches
die; leaves wither and turn brown; infected bark
is sunken, and wrinkled, with small black
pycnidia breaking through. On larger stems the
bark has a ridge of callus around the canker, the
sapwood in this area turning dark with black
streaks extending longitudinally for several
inches. Numerous water-sprouts grow from
below the dead crown. The fungus winters on
dead twigs, producing a new crop of conidia in
spring, readily infecting most trees weakened by
unfavorable environmental conditions.
Control
Prune out diseased portions at least 6
inches below cankers. Fertilize and water to
improve vigor. Remove seriously diseased trees.
Botryosphaeria rhodina (formerly
Physalospora rhodina
).
Black Rot Canker
of
tung in Mississippi and Louisiana. Black, sunken
cankers on trunks, limbs, twigs, and shoots, may
girdle and kill trees. Rogue and burn diseased
specimens.
Glomerella cingulata (formerly
Physalospora
miyabeana
).
Willow Black Canker
, accompany-
ing scab to form the disease complex known as
willow blight in New England and New York.
Starting in leaf blades, the fungus proceeds
through petioles into twigs; it also causes cankers
on larger stems, followed by defoliation. Pinkish
spore masses of the anamorph
Gloeosporium
state are formed on dead twigs and branch can-
kers and then short-necked perithecia, which
overwinter. Remove and destroy dead twigs and
branches during the dormant period. Spray 3
times with bordeaux mixture, starting just after
leaves emerge in spring.
Physalospora cortices (see
scab to form the disease complex known as wil-
low blight in New England and New York.
Physalospora obtusa (
Sphaeropsis malorum
)
(see
Botryosphaeria obtusa
).
Dieback
,
Canker
of hardwoods, New York Apple-Tree Canker,
Black Rot of Apple.
Physalospora rhodina (see
▶
Botryosphaeria
rhodina
).
Black Rot Canker
of tung in Mississippi
and Louisiana.
▶
Phytophthora
Blights
.
Phytophthora cactorum
Bleeding Canker
of
maple, beech, birch, elm, horsechestnut, linden,
oak, sweetgum, and willow;
Crown Canker
of
dogwood;
Dieback
of rhododendron; Trunk Can-
ker of apple, almond, apricot, cherry, and peach.
Bleeding Canker
, first noticed in Rhode Island
on maple about 1939 and found in New Jersey the
next year, is now present on many trees in the
Northeast. The most characteristic symptom is
the oozing of a watery light brown or thick red-
dish brown liquid from fissures in bark at the root
collar and at intervals in trunk and branches.
When dry, this sap resembles dried blood, hence
the name, bleeding canker. Sunken, furrowed
cankers are more definite on young trees than on
older trees with rough bark. Symptoms are most
prominent in late spring and early fall, with trees
in moist situations most often affected. The fun-
gus lives in the soil and advances upward from
a primary root infection. Wilting of leaves and
blighting of branches is evidently from a toxin.
Mature trees have fewer, smaller, yellow-green
leaves, and there is an acute dieback of branches.
Reddish-brown areas with intense olive-green
margins are found in wood extending vertically
from roots to dying branches, marked at irregular
intervals with cavities containing the watery
fluid.
Control
Although there is no real “cure,”
injecting trees with Carosel, a mixture of helione
orange dye and malachite green, has inhibited the
fungus and neutralized the toxin. In some cases
trees recover without treatment. Avoid heavy
feeding; this seems to encourage the spread of
▶
Botryosphaeria
corticis
).
Blueberry Cane Canker
, in Southeast
on cultivated blueberries.
Physalospora
▶
glandicola (
Sphaeropsis
quercina, Anamorph
)
Botryosphaeria
quercuum
).
Sphaeropsis Canker
,
Dieback
of
red, chestnut, and other oaks.
Physalospora miyabeana (see
(see
▶
Glomerella
cingulata
).
Willow Black Canker
, accompanying
▶
