Yellow Starthistle, Centaurea  solstitialis L., non-native
- a dicot in the Asteraceae family -

One of the major goals of the Four Creeks Chapter of the Sierra Los Tulares Land Trust, which manages Kaweah Oaks Preserve, is to control invasive weed species. On the top of this list is yellow star thistle. We have used several methods in the past including physical removal, flail mowing, and spot treatment with chemicals. We may have some small scale experiments using fire in the future. We have also been cooperating with the Agricultural Commissioner's Office's Biological Control Program on the release of insects that destroy the flower head of yellow star thistle and/or the seeds. 

Control of this weed will be an on-going process that will not be accomplished in one year or even a few years.  It will require long-term dedication and, most likely, there will be years when control is better than others. 

Carol Frate; President, Four Creeks Chapter
yellow starthistle is inpenetrable is parts of the preserve
Yellow starthislte flower on left, grows in great colonies on west meadow.

YST is inside the outlined area. (Daniel Benoy for perspective!)



 
 
 
 
 

YST inside outlined area
Yellow Star Thistle grows to 3 feet tall in the summertime. It is stiff and well branched, with bright sunflower yellow flowers. Flowers have sharp spikes radiating from its base.
- thus the name "Star" thistle.

 
 

no flower budsDennis Haines,
Above left: Mature YST without flower buds - obvious impact of IPM.
Above right: Dennis Haines, Agricultural Staff Biologist with the
Agricultural Commissioner's Office of Tulare County

Bangasternus  orientalis egg massesBangasternus  orientalis pupa

adult Bangasternus  orientalis


Above left: At base area of flower notice the three black egg masses of the Flowerhead Bud Weevil, Bangasternus  orientalis.

Above right: The Flowerhead Bud Weevil pupa.

Right: Adult Flowerhead Bud Weevil, Bangasternus  orientalis
 
 

Beneath the moist area you could find the larva of the False Peacock FlyAdult female False Peacock Fly

Above left: Evidence of False Peacock Fly larva on YST bud.

False Peacock Fly
Adult False Peacock Fly, Chaetorellia  succinea
  - female?(pointed object is a yst thorn)
 
 





Adult pair of Hairy WeevilsMature Hairy Weevil
Above: adult hairy weevils, Eustenopus  villosus
Close-up of Hairy Weevil snoutHairy Weevil by penny
Left: That's quite a nose! Right - Hairy weevil posed next to a penny for size comparison.



Click on the links below for more yellow starthistle (YST)
information, its biology and control:
UC Davis YST webpage Weed RIC - UC Davis / YST
YST Control for Homeowners More YST info
Purdue University
CERIS weed bio-control links


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