Q: I have many, many feet of liriope lining my driveway. A large section of it suddenly started turning yellow. When you gently pull on it, it breaks away easily and has a black area at the base where it breaks. Any suggestions?

A: Most gardeners consider the plant bullet-proof but you are not the first to complain about dying liriope this season. The disease you describe is crown rot, caused by Phytophthora palmivora. The disease is exacerbated by wet soil so don’t do any irrigation for the rest of the summer. Fungicide drenches can control the disease but they are too expensive to consider. One source reports that compost tea or a topdressing of compost can help the monkey grass recover. If you decide to replace the plants, add plenty of coarse sand (Pavestone Paver Leveling Sand is one source) to the spot to increase drainage.

See also

Leaf and Crown Rot of Liriope