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New invasive plants for 2006 …
Yellow Starthistle
Centaurea solstitialis
Jamie M. Snyder
University of Alaska Fairbanks
Cooperative Extension Service
[email protected]
Background:
• Starthistle in nursery stock
• Not Ranked in AK
– Hot, dry, light-intensive areas
– Adapted to monopolize soil moisture
– Seedlings survive extended frost, mature
plants not frost tolerant
• Starthistle response to summer 2006
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Rosette stage:
Cindy Roche, www.forestryimages.org
Origins:
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Native to N. Africa, S. Europe, W. Eurasia
1600s- Introduced from Spain to Chile
1800s- Chile to California
1930s- fields and roadsides -> foothills
• Today: Infests 15
million acres in
California,
41
States, and Canada from
BC to Ontario.
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Identification:
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Gray-green to blue-green
Grows 6” to 5 ft, branching form
Extremely deep tap root
Yellow flowers, sharp spines at base
“Winged” stems
Basal leaves deeply lobed, upper leaves
shorter and narrower
3 ft 3” and
Growin’ like a
weed…
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Impacts:
• Out-competes native plants
• Barrier to livestock & wildlife
• Reduces wildlife habitat and forage
• Reduces land values
• Depletes soil moisture
• Toxicity to horses
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Spread:
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Contaminant in grass seed, all classes of hay
Livestock, songbirds ingest seed & disperse
Farm, construction equipment
Roadsides
Microscopic barbs on pappus- adhere to
clothing, hair, and fur
• Seed production: over
50 million seeds per acre
in dense stands
Coming clean…
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Yellow starthistle (Centaurea solstitialis)
Sicilian starthistle (C. sulphurea)
Malta starthistle or “tocalote” (C.
melitensis)
Jack Kelly Clark, UC Davis Weed Science Program, University of California,
http://wric.ucdavis.edu/yst/images/clark/clark5.jpg
Thank You
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