Q: My yard is a haven for a week I do not recognize. It looks like a tiny mimosa tree. Can you offer any help?
A: Weed scientists call this plant chamberbitter but I call it mimosa weed, because it looks just like a little mimosa seedling. Mimosa tree seedlings, though, don’t have tiny yellow seeds under the mid-vein of each leaf. Your best bet is repeated applications of an herbicide that contains 2,4-D (Weed-B-Gon, Weed Stop, Wipe-Out, etc). They will control it, particularly if you start spraying when the weed is young.
The seeds need very warm soil in order to germinate so you won’t notice the seedlings until mid-summer. Researchers say pre-emergence herbicides that contain atrazine (Purge) on centipedegrass lawns and isoxaben (Greenlight Portrait, Gallery, etc.) on all turfgrasses give good results when applied in early May and again in mid-June.
You may find that simply pulling out the weed gives good enough results. Be sure to discard the plants immediately; don’t put them on your compost pile.