Land Plants - invasive

Yellow Starthistle (Centaurea solstitialis) on Jul 29, 2009

Submitter has sample
EDRR Status: Local expert notified

Description of specimen

Small 20' x 40' patch of Yellow Star Thistle.


This patch on County land could be easily removed, but I was told that it would not be due to costs involved. I was told that it might be sprayed if someone happpened to be in the area. At this point, I doubt that spraying will work because it has already formed it's thistles but still has some yellow flowers. It needs to be totally removed before it spreads. It seems a waste of time to report these things if nothing will be done.

July 29, 2009, 9:53 a.m.

Dear Ed,

I am sorry for the late reply to your report! Yes, yellow starthistle is an incredibly damaging plant and we need to prevent it from spreading further. I can truly understand your frustration seeing it allowed to spread. The problem is that in that area there is already so much starthistle, invasive species managers with limited resources have to prioritize by focusing control efforts on the outskirts of the populations or on species that are still not very abundant yet. So, the population you reported may not be prioritized for control because there are so many other yellow starthistle patches nearby. I am not really familiar with that particular site, however, so I will forward this report to local land managers in order to get a more definitive answer.
Yes, I can also understand your frustration about reporting species that are not going to get controlled. I believe there is value to reporting for two reasons. First, even if this population doesn’t get controlled, by reporting you are creating a public record of the population that allows people to map the infestation for strategic control, and increase awareness about invasive species in general. Once the report is public, then people will find these reports as they search the web. Maybe someone will start controlling yellow starthistle on their property as a result? Second, there are some very high priority species that if reported early, we could get to it right away and prevent a huge unmanaged infestation (imagine if we had gotten to yellow starthistle before it was too late!?).
Early Detection and Rapid Response is the most cost effective approach to invasive species, but we need people out there looking and reporting for it to work. There are a lot of species that are new to your area that if you found them we would definitely want you to report! In fact, the Jackson County Cooperative Weed Management Area has started and invasive watch program where they put on free trainings for people to learn what species to be looking for. The main contact for that program is Kai Victor ( (541) 770-7933 Ext. 5. The species in Jackson county that are considered high priority are listed below. We are working on creating a ID guide book for these species. When we finish we could mail you one! Please feel free to contact either myself or Kai if you would like more information or an ID guide.

Rush Skeletonweed Chondrilla juncea
Russian Thistle Salsola kali
Puncture vine Tribulus terrestris
Leafy Spurge Euphorbia esula
Dalmatian toadflax Linaria dalmatica
False Brome* Brachypodium sylvaticum
Whitetop Hoary Cress Cardaria draba
Garlic Mustard Alliaria petiolata
Cut Leaf Teasel Dipsacus laciniatus
Scotch Onopordum acanthium
Musk Carduus nutans
Wooly Distaff Carthamus lanatus
Italian Thistle
Duffuse knapweed Centaurea diffusa
Russian knapweed Acroptilon repens
Spotted knapweed Centaurea maculosa
Meadow knapweed Centaurea pratensis
Squarrose knapweed Centaurea virgata

Thanks again for your concern about invasive species. Please do keep on reporting and raising awareness!


Tania Siemens

WISE Program Coordinator
(Watershed and Invasive Species Education)
Oregon Sea Grant Extension

Western Oregon EDRR Coordinator
Early Detection and Rapid Response to Invasive Species
The Nature Conservancy

Tania Siemens
Aug. 7, 2009, 4:24 a.m.