Biology Reference
In-Depth Information
Didymaria didyma (see
Ramularia didyma
).
Leaf Spot
on anemone. Angular brown spots.
Ramularia didyma (formerly
Didymaria
didyma
).
Leaf Spot
on anemone. Angular brown
spots.
▶
Didymellina
Acomycetes, Sphaeriales,
Mycosphaerellaceae
Perithecia separate, innate or finally erumpent,
not beaked; spores two-celled, hyaline.
Didymellina
macrospora
(
Heterosporium
iridis, H.
Mycosphaerella
macrospora
, Anamorph).
Irish Leaf Spot
,
Blotch
,
Fire
on both bulbous and rhizomatous
iris.
Didymellina
gracilis
)
(see
▶
Fig. 3
Iris Leaf Spot
ornithogali (
Heterosporium
ornithogali
) (see
Mycosphaerella ornithogali
).
Leaf Spot
on star-of-bethlehem.
Didymellina poecilospora A weak parasite
sometimes causing black discoloration of iris
foliage.
Mycosphaerella macrospora (formerly
Didymellina macrospora
;
Heterosporium iridis,
H. gracilis
, Anamorph).
Irish Leaf Spot
,
Blotch
,
Fire
on both bulbous and rhizomatous iris. The
spotting is conspicuous toward the end of the
season but is not too serious in a normally dry
season. Usually the spots are confined to the
upper half of leaves, but if plants are crowded
and shaded and the summer is wet, the spotting
appears earlier, covers more of the leaf, and is
more damaging.
Spots are dark brown at first, surrounded by
a water-soaked and then yellowing region; they
enlarge into rather oval lesions, up to 1/2 inch
long, with a red-brown border (
Fig. 3
). Flower
buds and stems of bulbous iris may be attacked.
Tufts of olive conidia turn the centers grayish, the
spores being produced in abundance and splashed
by rain to neighboring leaves. Infection is
through stomata or directly through the epider-
mis. The fungus winters as mycelium in old
leaves, and in spring produces a fresh crop of
conidia or perithecia of the
Didymellina
stage.
▶
Soils deficient in lime apparently favor the dis-
ease. Repeated spotting reduces bloom and, after
a number of years, may kill plants.
Control
It is often sufficient to remove and burn
all old leaves at the end of the season; shearing
back spotted leaves in midsummer is helpful. If
the disease is regularly a problem, spray with
bordeaux mixture, starting when fans are 6 to
8 inches high and repeating at 10-to 14-day
intervals.
Mycosphaerella ornithogali (formerly
Didymellina ornithogali
;
Heterosporium
ornithogali
, Anamorph).
Leaf Spot
on star-of-
bethlehem. Occasional sooty spots on leaves,
with foliage blackened and killed in severe
infections.
Didymosporium
Deuteromycetes, Coelomycetes
Conidia are slime-spores
in acervuli; dark,
two-celled.
Didymosporium arbuticola
Leaf
Spot
on
Arbutus menziesii
.
