Biology Reference
In-Depth Information
Cankers and Diebacks
A canker is a localized lesion or diseased area
often resulting in an open wound and usually on
a woody structure. Starting as a definite necrotic
spot, it may girdle cane, stem, or tree trunk,
killing the water-conducting tissues so that the
most prominent symptom becomes a dieback.
When twigs and branches die back from the tip,
the condition may be a blight, with the pathogen
directly invading the dying area, or it may be
a secondary effect from a canker some distance
below.
light gray sunken areas in bark vary from several
inches to a foot across. The fungus is confined to
dead bark; trees are not injured.
Dendrothele acerina (formerly
Aleurodiscus
acerina
).
Bark Patch
, wide-spread on maple.
Amphobotrys
Deuteromycetes, Hyphomycetes
Conidiophores are long, slender, pigmented, and
highly branched; clusters of conidia at apex of
each branch; conidia ovoid, one-celled, hyaline.
Amphobotrys ricini
Stem Canker
on
texasweed and castorbean. Girdling stem canker;
of prostrate spurge.
Aleurodiscus
Basidiomycetes, Aphyllophorales
Hymenium resupinate, of one layer, with
projecting spinose or short-branching cystidia
(swollen sterile cells); spores hyaline. Facultative
parasite on trees.
Aleurodiscus
Apioporthe
Dendrothele
acerina
).
Bark Patch
, wide-spread on maple.
Aleurodiscus amorphus
Balsam Fir Canker
.
Cankers are formed on main stems of saplings,
which are sometimes killed, but the fungus is also
widespread as a saprophyte on dead bark of firs
and other conifers. Cankers center around a dead
branch, are narrowly elliptical with a raised bor-
der; the dead bark is covered with a light-colored
layer of the fungus.
Aleurodiscus oakesii
Oak Bark Patch
,
Smooth
Patch
of white oak. Irregularly circular, smooth,
acerina (see
▶
Ascomycetes, Diaporthales
Perithecia in a black, carbonaceous stroma;
spores two-celled, hyaline; conidia in cavities in
a stroma.
Anisogramma anomala (formerly Apioporthe
anomala).
Canker
,
Twig Blight
of hazelnut.
Apioporthe
Anisogramma
anomala
).
Canker
,
Twig Blight
of hazelnut.
Apioporthe apiospora
Twig Canker
,
Dieback
of elm.
anomala (see
▶
