Landscape Literacy

Perennial Problems: Leaf and Crown Rot of Liriope

Liriope is a great perennial to add to your landscape. Like any plant, however, it is susceptible to disease. Leaf and crown rot of liriope is a common ailment and needs to be safeguarded against. This disease is caused by a pathogen called Phytophthora palmivora, which is the culprit of root and crown rot in many plants. Unfortunately, leaf and crown rot is a hard disease to spot until the late stages of disease development. Affected leaves turn a yellow color, beginning at the base, then eventually turn brown as the watery rot develops.

Leaf and crown rot of liriope develops typically in late spring to early summer when we encounter the longest periods of rain and temperatures are rising. The disease can develop well into the fall and only decreases when temperatures are cooler. Any patch of your landscape that is susceptible to standing water is more likely to experience leaf and crown rot. Pots or areas of more organic matter tend to hold water longer, which can also cause disease development. Planting too many plants within the same area or planting too deeply can also stem disease growth.

The primary treatment for leaf and crown rot is through the use of fungicides such as mefenoxam, fosetyl-Al and the phosphite fungicides. While fungicides do not eradicate the pathogen, regular application by a professional can improve the plant’s prospect. Using disease-free material and avoiding the spread of the pathogen are good practices to maintain with any plant, since the disease can be hard to get rid of once it invades. Learning how to identify and manage this disease can help your landscape in the long run.

Photo by Dr. Donald M. Ferrin via The LSU AgCenter.