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Starthistle removal #878675

Asked July 25, 2024, 3:53 AM EDT

What is the best way to remove star thistles? They are a lot of starthistles in my land . Does solarization kill the roots?

Jackson County Oregon

Expert Response

Greetings,

The attached publication covers the history of yellow starthistle (Centaurea solstitialis L.) invasion of the Pacific Northwest and describes current infestation levels in Oregon and Washington. Provides basic information regarding yellow starthistle ecology, including descriptions of habitat, seed production, seed dispersal, germination and viability, seedlings, rosettes, and adults. Discusses yellow starthistle management strategies, including prevention, containment, and chemical, mechanical, and biological control. Includes sources for further information.
Warm Regards,  Replied July 25, 2024, 1:21 PM EDT
Dear Teagan,

Thank you again for your reply.

Can I ask one more question about removing starthistles?
I placed black tarp after mowing the thisttles, for a few weeks or a month. 
It looks there are no thistles growing and the ground looks very flat, without any weeds!

I would like to know if all the roots are removed by this solarization...
I would also like to know if I should keep the tarp throughout fall and winter.

If you could advise me, that'll be greatly appreciated.

Thank you very much.
Masako

PS. Is it OK to share the articles and your advise with my friends who have the same issue?

On Thu, Jul 25, 2024 at 10:21 AM Ask Extension <<personal data hidden>> wrote:
The Question Asker Replied September 27, 2024, 2:18 AM EDT
Hi,  There are several variables that determine how slow or fast roots break down ( soil biome, heat, moisture).  You may just want to sample some areas to see if there is any root mass left in the soil. Here is some additional information that may be helpful.  
https://cesanjoaquin.ucanr.edu/?blogpost=43014&blogasset=13682

Thanks 
Amy Jo Detweiler,  Professor and Extension Horticulturist Replied October 17, 2024, 6:11 PM EDT
Hi

I have further questions about starthistle removal.

I can mow the thistle with mower. But leaving mowed materials don’t seem to help. It came back to grow. I am aware that there are dormant seeds in the ground.

I would like to experiment “ hot composting” the thistles. If you have some tips I would it.

Also I would like to learn solarization with plastic sheets after weeding. If you can advise some tips please let me know.

I also would like to know if there is weeds disposal place in Jacksonville county

Thank you 
Masako 

Sent from my iPhone

On Oct 17, 2024, at 3:11 PM, Ask Extension wrote:


The Question Asker Replied August 01, 2025, 4:30 PM EDT
Hi Masako,   Here is a publication on composting that  may be helpful.  https://smallfarms.oregonstate.edu/sites/agscid7/files/eb1784e.pdf

You will need to contact the your local disposal company to find out about weed disposal:  https://jacksonvilleoregon.org/business-directory/rogue-disposal-and-recycling/ 

Thanks  

Amy Jo Detweiler,  Professor and Extension Horticulturist Replied August 04, 2025, 1:26 PM EDT

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