Q: I looked up the mimosa-like weed that was mentioned in your newspaper column and found it to be chamberbitter. It is all in my lawn and flower beds. Now that I know what it is, how do I kill it?
A: Chamberbitter (Phyllanthus urinaria) is a tropical weed that has become a major pest of lawns, landscapes and plant nurseries. Glyphosate (click for sources) will kill it but you have to be careful to keep the non-selective chemical off nearby foliage.
In a lawn, use one of the “three way” broadleaf weed killers (click for sources) on your weeds instead. In the last few years, “four way” weed killers have been introduced: BioAdvanced Season Long Weed Control (click for sources) and Bonide Weed Beater Ultra (click for sources). Atrazine (click for sources) is labeled for broadleaf weed control in centipede and St. Augustine lawns.
An effective organic herbicide is iron chelate (FeHDTA, Bonide Weed Beater Fe, Natria) (click for sources). See photos below provided by Chris T.
The best way to control the weed is to prevent it. Apply isoxaben (click for sources) pre-emergent herbicide in March and again in early June to areas where you will not be planting seeds for anything else. As with every herbicide, read the label and follow it exactly.