Biology Reference
In-Depth Information
Needle Casts
Bifusella
Certain diseases of conifers that result in conspic-
uous shedding of needles are termed needle
casts, sometimes needle blights. Most of the
fungi causing such symptoms are members of
the Phacidiales.
Ascomycetes, Rhytismatales
Apothecia elongate, slitting with a cleft; paraph-
yses lacking; spores hyaline, one-celled, club-
shaped at both ends with halves joined by
a narrow neck (
Fig. 1
).
Bifusella abietis (see
Phaeocryptopus (Adelopus)
Isthmiella abietis
).
Nee-
dle Cast
of fir on alpine and corkbark fir from
New Mexico to Idaho.
Bifusella faullii
▶
Ascomycetes, Dothideales
One of the black mildews, with superficial,
dark mycelium; perithecia innate with a central
foot, without ostiole; spores two-celled, hyaline.
Adelopus gaumannii (see
Isthmiella faulii
).
Needle
Cast
of Balsam fir, the most common and destruc-
tive of the needle casts of this host.
Bifusella linearis
Needle Cast
of pine,
Tar
Spot
, on various pine species. Hysterothecia are
variable in length, shining black, on two-year
needles.
Bifusella saccata
Needle Cast
on pine.
Isthmiella abietis (formerly
Bifusella abietis
).
Needle Cast
of fir on alpine and corkbark fir
from New Mexico to Idaho. Dark brown to
black hysterothecia extend the entire length of
the middle nerve on undersurface of needle.
Pycnidia are in two rows on upper surface.
Isthmiella faulii (formerly
Bifusella faulli
).
Needle Cast
of Balsam fir, the most common
and destructive of the needle casts of this
host. Ascospores are discharged in July, but
infected young needles do not change color
until spring, then turn light brown to buff.
Effused pycnidia in the same color appear in the
groove on upper surface of the needle, followed
(see
▶
Phaeocryptopus
gaeumannii
).
Adelopus Needle Cast
of Doug-
las-fir,
Swiss Needle Cast
.
Phaeocryptopus
▶
gaeumannii (formerly
Adelopus g
aumannii
).
Adelopus Needle Cast
of
Douglas-fir,
Swiss Needle Cast
. Although
first noted in Switzerland in 1925, this seems
to be a native American disease occurring in
relatively harmless fashion on the Pacific Coast,
somewhat injurious to native Douglas-fir in the
Southwest and to trees in New England and New
York. Needles fall prematurely, leaving only the
current season's growth. If this happens for sev-
eral consecutive years, trees have thin foliage,
appear yellow or brown, and finally die. Needles
are yellow-green to brown, often mottled, and on
undersurface tiny black perithecia, issuing from
stomata, appear as sooty streaks, one on each side
of the middle nerve.
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