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• What
is a Weed Management Area
• Why
is it important to control invasive weeds
• Who
belongs to the Los Angeles County WMA
• Weed
Management Area Activities
• Major
Invasive Weeds in Los Angeles County
• Other weeds of concern
• What
can you do to help?
• Download
the LA County WMA Information Pamphlet
• Children's
book on invasive weeds
• Download:"Best
Management Practices for Vegetation Management" (PDF/6.5
MB/56 Pages)
• Links
Geraldton Carnation Spurge (Euphorbia
terricina)
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Geraldton Carnation
Spurge is a fairly recently discovered invasive
weed that is currently rated "Q" by
the California Department of Food and Agriculture.
This pest designation means that the pest is new
to the state and its seriousness as a pest is
being evaluated. This plant is native to the Mediterranean
coast of Europe. Like other members of the Euphorbia
family, broken stems exude sticky white sap. The
sap of Carnation Spurge is toxic and can cause
temporary blindness if allowed to come into contact
with the eyes. Stock that graze heavily or eat
infested hay may be poisoned. It gets its start
in disturbed sites along roadsides, trails, firebreaks
and riparian areas.
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Geraldton
Carnation Spurge a serious
new threat to the Malibu area
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This plant spreads very quickly and
replaces native plants that provide food shelter and
other resources to native animals. Geraldton Carnation
Spurge infests the Malibu drainage down to the El Segundo
Dunes and has been found in Monterey Park and City Terrace
area.
Giant Reed (Arundo donax)
A
mature stand of Arundo near Chantry Flats
in the Angeles National Forest
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Arundo
or Giant Reed is a large, thick-stemmedgrass, that
grows in flood plains and riparian areas. It looks
like bamboo and is often mistaken for it. It is
native to Asia and was once used to control erosion.
It can grow to 30 feet tall and produces no viable
seed, but spreads vegetatively by using underground
stems called rhizomes. Arundo is one of the fastest
growing plants in the world--under ideal growing
conditions it may grow up to 4 inches a day. |
It forms large colonies that displace
other plants and provide virtually no habitat or food
for wildlife. Arundo is highly flammable, which encourages
fire along streams and can further degrade riparian
habitat. This is Los Angeles County's most hated invasive
weed. More time and resources are being expended on
the eradication of this one plant than any other.
Castor Bean ( Ricinus communis)
| Castor
bean is originally from tropical Asia and Africa.
It was grown as an agricultural crop for its oil,
but it escaped from cultivation and began to spread
into disturbed areas in the San Joaquin Valley and
coastal regions of Southern California. The crop
report from L.A, County from 1881 notes that 900
acres of castor bean plant yielded 1.2 million pounds
of seed. Not only does it displace native plants
by forming large colonies, but it is one of the
first plants to germinate after a fire. Through
rapid growth, it out competes native vegetation
and creates new infestations where previously there
had been only healthy native plants. |
A
mature caster bean plant
infesting a riparian area
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Castor bean seeds are extremely poisonous
to humans, cattle, horses, rabbits, sheep, pigs, goats,
cats, dogs, and poultry. Two beans, if ingested, can
be lethal in humans.
Perennial Pepperweed (Lepidium latifolium)
A
Perennial Pepperweed in bloom
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Perennial Pepperweed
is a native of Eurasia and infests brackish to
alkaline wetlands throughout California. It is
a multi-stemmed plant that grows from 3 to 8 feet
in height. Pepperweed forms dense colonies that
displace native plant species, and it acts as
a "salt pump" by bringing salt ions
from deep in the soil up through its root system
and depositing them in the top soil. This changes
the soil chemistry by making it more alkaline.
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Yellow Starthistle (Centaurea
solstitalis)
Tocolote
(left) is often confused
with Yellow Starthistle
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YST
Flower
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CDFA
biocontrol specialist Baldo Villegas
checking for evidence of Hairy Weevil
feeding on YST in Calabasas
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Yellow Starthistle is native
to southern Europe and western Eurasia. It likes
to colonize disturbed areas and moves into annual
and perennial pastures. It forms dense, spiny,
infestations that displace native plants and animals,
threatening natural ecosystems and nature reserves.
Yellow Starthistle can significantly deplete soil
moisture reserves in the grasslands they infest.
This plant is toxic to horses and long term consumption
can cause a neurological disorder known as chewing
disease. Not only does Yellow Starthistle reduce
the quality of the land it infests, it also limits
the recreational value by creating impenetrable
barriers.
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YST
infesting a field in Diamond Bar
in the 1950's
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For more information on invasive
weeds, including biology and control of listed weeds,
look at the encycloweedia located at the California
Department of Food and Agriculture website at http://www.cdfa.ca.gov/wma
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