Q: I have tried through every source that I know to identify this weed. I have been told that is germinates in the thatch of lawns and mulch and is not controlled by pre-emergent. Please give me the name and tell me how to control it.
A: It’s burnweed, Erechtites hieracifolia. When it flowers you’ll see characteristic “bundles” of seed at the top of a 3′ – 5′ tall plant. The seed float in the breeze, much like a dandelion. Due to the multitudes of seed produced, it only takes one plant to infest a neighborhood.
You can control it with a pre-emergent (click for sources) designed for broadleaf weeds, applied in March…but the weed is so easy to pull, I’d try hand weeding at first.
If the plants are too numerous, glyphosate (click for sources) spray would work.