This weed, which we call "The Tumor" (in your best Arnold
Schwartzenager voice) is drivng us nuts. It comes on super fast,
grows super fast and returns after we pull it out. Its got prickly
edges. See phot link below.

Is there a chemical based weed killer that can take this out? Preen
did nothing to it. This weed just laughed at Preen.

http://ucemergencymedicineorg.siteprotect.net/weed.jpg


From the picture, this looks like a few seconds with the hoe, they are
gone, although temporarily. No chemicals needed. But to remove a
unwanted plant that is growing with iris, grass, etc. is a bit
tougher. Roundup will kill the root. Be careful with overspray, or
you can paint the leaves using a paint brush/sponge and rubber gloves.
Established thistles are tough--I have tried flame torching with
limited success. I have not tried Preen--isn't that a pre-emergent
product?