Biology Reference
In-Depth Information
Didymosphaeria
Dothistroma
Ascomycetes, Dothideales
Deuteromycetes, Coelomycetes
Perithecia innate or finally erumpent; not beaked;
smooth; paraphyses present; spores dark, two-
celled.
Didymosphaeria populina (
Venturia populina,
V. tremulae, V. macularis
also cause this disease).
Shoot Blight
of polar,
Leaf and Twig Blight
.
Young shoots are blackened and wilted. In
moist weather dark olive green masses of spores
are formed on leaves.
Stroma dark, elongate, innate, becoming
erumpent and swollen, with a stalk extending
into the substratum, composed internally of
dense, vertical hyphae; locules separate, one to
several in the upper part of the stroma; conidio-
phores simple, slender; conidia several-celled,
hyaline, long-cylindrical to filiform.
Dothistroma pini
Needle Blight
on Austrian
pine and red pine.
Cryphonectria (Endothia)
Diplodia
Ascomycetes, Diaporthales
Deuteromycetes, Coelomycetes
Perithecia deeply embedded in a reddish to yel-
low stroma, with long necks opening to the sur-
face but not beaked; paraphyses lacking; spores
two-celled, hyaline. Conidia borne in hollow
chambers or pycnidia in a stroma and expelled
in cirrhi.
Cryphonectria parasitica
Chestnut Blight
,
Endothia Canker
, general on chestnut. To most
gardeners this disease is of only historical impor-
tance, for practically all of our native chestnuts
are gone. The disease, however, persists in
sprouts starting from old stumps and in the chin-
quapin. One of the most destructive tree diseases
ever known, chestnut blight at least served to
awaken people to the importance of plant disease
and to the need for research in this field.
First noticed in the New York Zoological Park
in 1904, the blight rapidly wiped out the chestnut
stands in New England and along the Allegheny
and Blue Ridge Mountains, leaving not a single
undamaged tree. In 1925 the disease eliminated
chestnuts in Illinois and by 1929 had reached the
Pacific Northwest.
Conspicuous reddish bark cankers are formed
on trunk and limbs, often swollen and splitting
longitudinally. As the limbs are girdled, the
foliage blights, so that brown, dried leaves are
seen from a distance. The
Pycnidia innate or finally erumpent; black, single,
globose, smooth; ostiole present; conidiophores
slender, simple; conidia dark, two-celled, ellip-
soid or ovoid. Parasitic or saprophytic.
Some species cause twig blights which are not
too important: Diplodia coluteae on bladder
senna; D. longispora on white oak; Sphaeropsis
sapinea
(formerly
D.
pinea
)
on
pine;
D. sarmentorum on pyracantha.
Lasiodiplodia theobromae (formerly
Diplodia
natalensis
) (anamorph state of
Physalospora
rhodina
) causes blight, stem gumming, or stem-
end rot of melons, as well as twig blight of peach
and citrus. See further under
Rots
.
▶
Diplodia
Lasiodiplodia
theobromae
).
Blight
of slash pine and loblolly
pine seedlings.
Lasiodiplodia theobromae (formerly
Diplodia
gossypina
).
Blight
of slash pine and loblolly pine
seedlings
gossypina
(see
▶
Discula
Deuteromycetes, Coelomycetes
Discula quercina,
Twig Blight
of oaks.
fungus
fruits
