Biology Reference
In-Depth Information
Cytospora chrysosperma (Teleomorph,
Valsa
sordida
).
Cytospora Canker
of poplar, aspen,
cottonwood, willow, occasional on mountain-ash,
maple, cherry, and elder. Cankers form on trunks
and large branches, most often on trees of low
vigor. Bark is discolored in more or less circular
areas; sapwood is reddish brown. In old cankers
exposed wood is surrounded by layers of callus
tissue. In moist weather spring spore tendrils are
extruded from pycnidia in dead bark. Perithecia
are found infrequently in aspen, arranged circu-
larly around a grayish disc; they are flask-shaped
with long necks pushing through the bark. Twigs
and small branches may die back without
a definite canker. The fungus is often present on
healthy trees, not becoming pathogenic until the
trees are weakened by neglect, drought, pollarding
or other causes. Entrance is through wounds. Lom-
bardy and Simon poplars are frequently killed.
Control
Remove dead and dying branches and
trees with extensive cankers. Avoid wounds; feed
and water as necessary. Plant poplars that are less
susceptible than Lombardy. Rio Grande cotton-
wood is resistant to twig blight.
Cytospora kunzei (Teleomorph,
Leucostoma
kunzei
).
Cutospora Canker
of spruce.
Twig
Blight
, common and serious New England to the
Midwest. Cankers start around bases of small
twigs or on trunks. Browning and death of Colo-
rado blue spruce branches starts near the ground
and progresses upward, a large flow of resin on
affected limbs. Needles drop immediately or per-
sist for a time. Cankers are formed near resin
spots and yellow tendrils extruded. Spores are
splashed by rain and wind to other branches;
infection is mostly through wounds.
Another form of the pathogen,
Valsa kunzei
var.
superficialis
, occurs on pine and variety
kunzei
on balsam fir, Douglas-fir,
Cylindrocarpon
Rots
.
Cylindrocarpon didymium
Bole Canker
on
apple.
Cylindrocarpon cylindroides
Canker
,
Branch
Mortality
of
Abies
spp.
▶
Cylindrocladium
Blights
.
Cylindrocladium scoparium
Crown Canker
of
rose. The cane is attacked at or just below the
union of stock and scion, the bark darkening into
a black, water-soaked punky region. The cankers
girdle but do not kill the canes; there are fewer
and more inferior blooms. The disease was long
thought confined to greenhouse roses but has
appeared once or twice in outdoors fields. The
fungus lives in the soil and enters through wounds
in the presence of sufficient moisture. Before
planting of fresh stock, greenhouse benches
should be washed with boiling water and soil
sterilized or changed.
The same fungus injures seedling conifers in
nursery rows, causing damping-off, root rot, stem
canker and needle blight to white pine and Doug-
las-fir. See under
▶
▶
Cytospora
Deuteromycetes, Coelomycetes
larch and
Cosmopolitan species, anamorph state of
Valsa
.
Pycnidia in a valsoid stroma with irregular cavi-
ties, incompletely separated; conidia hyaline,
one-celled,
hemlock.
Control
There are no satisfactory control mea-
sures except removal of diseased branches and
perhaps carefully excising cankered bark.
Spraying with bordeaux mixture has been
recommended but is seldom very effective.
Avoid wounding ornamental trees with lawn
mowers; sterilize pruning tools between cuts;
feed to renew vigor.
allantoid,
expelled
in
cirrhi
(see
Fig. 1
).
Cytospora abietis
Canker
,
Branch Mortality
of
Abies
spp.
Cytospora pruinosa
Canker
,
Dieback
of ash,
on twigs and branches.
