GENEALOGY
Original sources for U.S.
release was Italy. First U.S. releases made in 1977. Established in
the Pacific Northwest, including Idaho, Oregon, and Washington.
Established in Stevens County.
LIFE
CYCLE
The fungus forms
infective spores within brownish pustules (uredia) on all above
ground parts of the plant. These infective spores are released from
the pustules from spring to fall to continue infection. Lesions (telia)
at the base of flowering shoots are another source of rust spores.
The overwintering stage is composed of dormant spores. In the spring
the overwintered spores germinate on rosette leaves, which
ultimately leads to the production of rust pustules (uredia) on all
plant parts, and lesions (telia) at the base of the flowering
shoots.
EFFECT
The pustules (uredia) and
the lesions (telia) are destructive. Infected seedlings may be
killed outright. Maturing plants have reduced vigor, reduced
photosynthetic surfaces, reduced root vigor, and their ability to
form viable seeds is hampered. Effects of the rust on Rush
Skeletonweed is diminished at hot and dry sites.
REDISTRIBUTION
Infected rosettes can be
collected and placed among uninfected plants during the spring and
fall. During the summer collect rusted plants and bind them into
"Teepees". Wedge these bundles into plants that are not
infected. Cooler weather, evening releases, and high humidity helps
the chances for establishment.
COMMENTS
This was the first plant
pathogen released for the control of a noxious weed in North
America.
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