Q: I have an aggressive weed in my lawn that I believe is yellow flowering wood sorrel. Can you suggest what I can use to kill the weed without harming my fescue?

A: Yellow woodsorrel, Oxalis stricta, sometimes called yellow clover, is tough to control. It arises from a taproot each year and scatters copious seeds during its blooming season.

In fescue you could use products containing triclopyr (click for sources). This can not be used on bermuda or centipede lawns. A non-chemical option is to nurture the fescue precisely to get dense growth that chokes out the woodsorrel.

For other grasses, products that contain sulfentrazone (click for sources) or carfentrazone (click for sources) or quinclorac (click for sources) may be useful.

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