Biology Reference
In-Depth Information
Puccinia aristidae and varieties II, III on wild
grasses,
Aristides
and
Distichlis
;0,Ion
eriogonum, greasewood, beet, spinach, western
wallflower, garden cress, radish, California blue-
bell, heliotrope, cleome, primrose, sand-verbena,
and others.
Puccinia asparagi
Asparagus Rust
. II, III gen-
eral on susceptible varieties; 0, I not reported in
natural infections. Also on onion. Asparagus
rust reached America in 1896 from Europe
and spread with devastating suddenness from
Boston and New Jersey to California, reaching
there by 1912, one of the fastest cases of disease
spread in our history. If tops are attacked several
years in succession, the root system is so
weakened that shoots fail to appear in spring or
are culls.
The first symptom is a browning or reddening
of smaller twigs and needles, with the discolored
area spreading rapidly until the whole planting
looks as if it had ripened prematurely. The red-
dish color is due to numerous small pustules of
urediospores that give off a dusty cloud when
touched. These appear in successive generations
until autumn, or a spell of drought, when they are
replaced by black teliospores, either in the same
or a new fruiting body. They remain on old stems
until spring, germinating then to infect new
shoots as they emerge from the ground.
Control
For a long time resistant varieties Mary
Washington and Martha Washington were the
answer to the rust problem, but the fungus has
developed resistant strains. Waltham Washing-
ton, Seneca Washington, and California 500
have some resistance. Clean up volunteer or
wild asparagus around beds. A parasitic fungus,
Darluca filum
, helps keep rust in check.
Puccinia brachypodii var. poae-nemoralis
(formerly
Puccinia poaenemoralis
(Syn.
P. poae-sudeticae
)).
Bluegrass Leaf Rust
,
Yellow
Leaf Rust
. II, III on turf grasses, mostly Canada
and Kentucky bluegrass; 0, I, unknown; general
east of the Rocky Mountains. The uredia are
orange-yellow with numerous peripheral paraph-
yses. Telia are covered rather permanently with
epidermis; spores are dark brown with short ped-
icels. The wheat stem rust is more important on
Merion bluegrass.
Fig. 4
Rust on Snapdragon
wild garlic, and wild onion. Uredia are yellowish,
telia black.
Puccinia amphigena (
Aecidium yuccae
). On
yucca.
Puccinia andropogonis, with various strains.
0, I on lupine, Indian paintbrush and turtlehead;
II, III on and ropogon.
Puccinia antirrhini
Snapdragon Rust
. II, III
general on snapdragon, also on linaria,
corydylanthus; 0, I unknown. Pustules of spores
on underside of leaves are chocolate brown, often
in concentric circles (see
Fig. 4
). The area over
the pustule is pale or yellow on upper surface.
Spores also appear on stems; there is a drying and
stunting of whole plant. The rust is spread by
wind-blown spores and on cuttings. For infection,
plants need to be wet with rain or dew 6 to
8 h with day temperatures around 70
to 75
F.
Spores are killed above 94
F. There are at least
two races.
Control
Purchase only rust-resistant variety.
Bordeaux mixture controls secondary fungi fol-
lowing rust but not the rust itself. Sulfur dust is
still useful, or a spray made by adding 1 ounce
rosin soap to a gallon of water and then adding 1
ounce dry lime sulfur.
Puccinia arachidis
Peanut Rust
, occasional in
Alabama, Florida, Texas.
