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Publications: Noxious Weeds
in Slow Motion: A
talk by Jerry Asher about noxious weeds in the Blue Mountains
Click on a weed to learn about how to find it and kill it!
- Stems: 1 to 6 feet tall, thinly covered by cobwebby hairs;
many branches near the top.
- Leaves: Divided into lobed and toothed segments, the
terminal lobe generally larger than the lateral. Stem leaves are
dark green, and ruffled, with blunt tips. First year plant is
a rosette with leaves up to 9 inches long.
- Flowers: Numerous heads. Flowers are yellow, 1-inch-wide,
and daisy-like. Flowering season in July through September.
- Seeds: Tiny, tipped with hair-like plumes that carry
them on the wind for long distances.
Every part of the Tansy Ragwort plant is poisonous; it causes liver
damage in horses and cattle. It spreads by seed; each plant can
produce 150,000 seeds that remain viable for 15 years.
- Biological: The cinnabar moth larvae feed on the leaves,
buds, and flowers; the ragwort seed fly larvae feed on the developing
seed; and the tansy ragwort flea beetle larvae feed on the roots
of the plant, and the adults feed on the leaves. These insects
complement each other. Introduction of competitive native vegetation
is also a good idea.
- Chemical: Certain herbicides readily kill tansy ragwort
seedlings. They are most effective before stem elongation. Tansy
ragwort dies slowly after herbicide application, and treated plants
are still poisonous 4 to 6 weeks after spraying.
- Mechanical: Cutting or mowing is only recommended when
other eradication methods are planned. Cutting does not kill the
plant, although if done before the early flowering period it will
reduce seed production. Pulling is worthwhile if the infestation
is very small, it is repeated consistently, and is followed up
with herbicide application. A thorough plowing each year can kill
most plants, and eventually deplete the seed stock.
Report all sightings to your local