Biology Reference
In-Depth Information
black, Japanese, and English walnut. The disease
was first described from Connecticut in 1923, but
evidently was responsible for slow dying of but-
ternuts long before that. If trees have been previ-
ously weakened, the fungus proceeds rapidly;
otherwise there is the slow advance of a weak
parasite. Dead limbs are sprinkled with small,
black acervuli, looking like drops of ink and
occasionally, in wet weather, developing spore
horns of olive gray conidia. In the teleomorph
state, which is rare, perithecia are embedded in
the bark singly or in groups. Mycelium invades
bark and wood, with a dark discoloration, and
grows slowly down a branch to the trunk. When
the latter is reached, the tree is doomed. In final
stages trees have a stag-headed effect from loss of
leaves.
Control
Remove diseased branches promptly,
cutting some distance below infection; remove
trees developing trunk cankers; keep the rest
growing well with food and water.
Macrophoma
Deuteromycetes, Coelomycetes
Like
Phoma
, with discrete pycnidia arising
innately, but with much larger spores; conidia
hyaline; one-celled.
Diplodia tumefaciens (formerly
Macrophoma
tumefaciens
).
Branch Gall Canker
of poplar.
Nearly spherical round galls, not over 1 1/2
inches in diameter, at base of twigs, which usu-
ally die; not serious.
Macrophoma candollei Associated with
Die-
back
of boxwood but apparently saprophytic
only. The large black pycnidia are, however,
quite striking on straw-colored leaves.
Macrophoma
cupressi
Dieback
of
Italian
cypress.
Macrophoma phoradendron Defoliates mis-
tletoe, but it grows back.
Macrophoma
Diplodia
tumefaciens
).
Branch Gall Canker
of poplar.
tumefaciens (see
▶
Meria
Massaria
Deuteromycetes, Hyphomycetes
Ascomycetes, Pyrenulales
Hyaline mycelium, branched; conidiophores sim-
ple, septate; conidia hyaline, one-celled, pro-
duced singly or in clusters.
Meria laricis,
Dieback
and
Blight
, on western
larch seedlings.
Spores dark, with several cells, oblong-fusiform,
with mucous sheath.
Massaria
Splanchrorema
platani
).
Canker
, widespread on branches of
American, London, and California plane trees.
Splanchrorema platani (formerly
Massaria
platani
).
Canker
, widespread on branches of
American, London, and California plane trees.
platani (see
▶
Monochaetia
Deuteromycetes, Coelomycetes
Acervuli dark, discoid or cushion-shaped, subcu-
taneous; conidia several-celled, dark median
cells, hyaline end cells, and a single apical
appendage; parasitic.
Monochaetia mali (see
Melanconis
Ascomycetes, Diaporthales
Seiridium unicorne
).
▶
Perithecia in an immersed black stroma; paraph-
yses present; spores two-celled, light; conidia
superficial on a stroma.
Melanconis juglandis
Walnut Canker
,
Butter-
nut Dieback
, widespread on butternut, also on
Canker
,
Leaf Spot
of apple.
Seiridium unicorne (formerly
Monochaetia
mali
).
Canker
,
Leaf Spot
of apple. Fungus enters
through deep wounds and grows into wood, then
attacks resulting wound callus and produces
