Biology Reference
In-Depth Information
Milesina laeviuscula
Needle Rust
. 0, I on grand
fir; II, III on licorice fern, in West.
Milesina marginalis 0, I on balsam fir; II, III on
Dryopteris marginalis
. Pycnia are on both sides
of needles, aecia of needles of current year,
maturing by midsummer.
Milesina pycnograndis (
M. polypodophila
). 0,
I on balsam fir; II, III on
Polypodium
virginianum
. Hyphae are perennial in needles
and small stems of balsam fir; aecia on needles
3 to 9 years old.
cells, each with two or three lateral pores; walls
somewhat layered, inner layer colored, outer
nearly colorless, smooth or verrucose; pedicel
colorless except near spore; often swelling in
lower portion (see
Fig. 3
). Aecia with catenulate
globoid or ellipsoid verrucose spores; uredia
when present circled with paraphyses; uredio-
spores single on pedicels, walls verrucose or
echinulate with indistinct scattered pores.
Phragmidium americanum 0, I, II, III on
leaves of native and cultivated roses. Teliospores
with eight to eleven cells.
Phragmidium fusiforme (
P. rosae-acicularis
).
0, I, II, III on several hosts species. Teliospores
with five to eleven cells, walls chocolate brown,
verrucose.
Phragmidiummontivagum 0, I, II, III on many
species of roses. Teliospores with six to nine
cells.
Phragmidium mucronatum (
P. disciflorum
).
Leaf Rust of Rose
.0, Ion leaves and stems; II, III
on leaves of cultivated roses, eastern states to the
Rocky Mountains and on the Pacific Coast. This
is the common rust of hybrid teas and other roses
with large, firm leaflets. It is not much of
a problem in the East, although sometimes
found in New York and New England gardens,
but it is a serious menace along the Pacific Coast.
Aecia appear on leaves as small, roughly circular
spots, 1/25 inch across, bright orange on the
underside of leaf, from the spore masses, light
yellow on the upper surface, sometimes bordered
with a narrow green zone. Leaf lesions may be
slightly cup-shaped viewed from the upper sur-
face. Stem lesions are long and narrow. The sum-
mer uredial stage has reddish orange spores in
very small spots, 1/50-inch, over underside of
leaves. This stage may repeat every 10 to 14
days in favorable weather, with wilting and defo-
liation. In mild climates the uredial stage con-
tinues; in cooler areas the telial stage is formed
toward autumn -black pustules of stalked dark
spores, rough, with a point, five to nine cells.
The leaf surface must be continuously wet for
4 h for rust spores to germinate and enter the leaf;
this means liquid water and not high humidity as
with mildews. High summer
Nyssopsora
Puccinaceae. Autoecious; teliospore with three cells.
Nyssopsora clavellosa
III on
Aralia hispida
.
Peridermium
A form genus with 0, I, on Gymnosperms. Aecia
have peridia and are cylindrical, tonguelike or
bullate.
Peridermium bethelii On dwarf mistletoe.
Peridermium ornamentale
0,
I on white,
alpine, and noble firs.
Peridermium rugosum 0, I on Pacific silver
and lowland white firs.
Phakopsora
Melampsoraceae. Telia indehiscent, lenticular;
spores formed in irregular succession, not
in
chains.
Phakopsora cherimoliae On cherimoya.
Phakopsora jatrophicola On cassava.
Phakopsora pachyrhizi On soybean.
Phakopsora
zizyphi-vulgaris On
Zizyphus
jujuba
, Florida.
Phragmidium
Pucciniaceae. Autoecious. Pycnia subcuticular,
other sori subepidermal; aecia caeomoid; telio-
spores large, conspicuous, of one to ten or more
temperatures
adversely
affect
infection,
summer
spores
