Starthistle Management

Starthistle Management: Yellow Starthistle Control

To control starthistles, develop a 3-5 year plan that includes intensive management for 2-3 years and follow-up treatments and monitoring for the next few years. Integrate strategies (fire, herbicides, reseeding) where possible. For long-term starthistle control, replant with perennial grasses.

Yellow starthistle (Centaurea solstitialis) is one of the Southwest's “Dirty Dozen” invasive weed species. Other invasive starthistle species include Malta starthistle or tocalote (C. melitensis), Sicilian thistle (C. sulphurea), Purple starthistle (C. calcitrapa) and Iberian starthistle (C. iberica).
Only a small percentage of starthistle seeds remain viable for 10 years or longer. Depletion studies suggest that 2-3 years of control may eliminate more than 95% of the seedbank in a treated area.
Appropriate control treatments for starthistle depend on growth stages, which, in turn, depend on temperature, rainfall and other cultural and environmental factors.

Mowing and burning are most effective when plants are in the late spiny and 2% flowering stages.
Chemical treatment varies by herbicide, but generally is most effective from the seedling/rosette stage to 2% flowering stage. Some herbicides that have proven effective are Picloram, Clopyralid, Curtail, 2,4-D and Glyphosate.

Read the label. You must follow the label directions for all pesticides to get the best results. Failure to follow labeled instructions may result in poor control, environmental damage, and wasted time, money and resources. If you have questions, contact a crop consultant, Extension specialist or County Extension Agent.
Grazing and hand pulling work best when plants are bolting. During this stage, plants provide a good protein source for ruminants. Yellow starthistle is toxic to horses.
Controlled fire may be used most effectively from late spiny to very early flowering.
Yellow starthistle responds well to early season biocontrol, using insects that feed on seed heads, such as the Hairy weevil (Eustenopus villosus) and False Peacock Fly (Chaetorellia succinea).

For more information, contact an Extension Specialist or your County Extension Agent.

Southwestern Noxious/Invasive Weed Starthistle Excerpt:

Excerpted from a July 2004 presentation short course, Farmington, NM, by Stephen Enloe, Extension Weed Specialist, University of Wyoming, sfenloe@uwyo.edu

Click the following link to listen to the audio excerpt: Yellow Starthistle

Click for problems with the audio file.

	Narrator: Yellow starthistle has invaded from 15 to 20 million acres of annual grasslands in California and is encroaching on other Western States.
	Steven Enloe: I'd call that a pretty darn aggressive invader. So when we see one starthistle acting like that, it automatically throws up a red flag in our minds that other types of starthistles may be able to do the same thing. So if we don't have that sort of problem yet, we don't want them to get to that level so we want to go after them aggressively when we see very small infestations.
	Narrator: To control this aggressive invader, develop a 3 to 5 year, multi-strategy management plan. For more information, contact a state Extension specialist or your local County Extension Agent.

Problems with audio files

If the video is not playing, it may be because you do not have the QuickTime player (or the latest version of it) installed on your machine.
Click here to download QuickTime for Macs.
Click here to download QuickTime for Windows PC.