Creeping phlox is the common name used for Phlox stolonifera and P. subulata, which is also called Moss Pink. Both form mats of evergreen foliage and bloom in the late winter or early spring. Both have blooms in shades of purple, pink, red and white.
P. subulata is about 6 inches tall and prefers full sun. P. stolonifera is about 12 inches tall, grows in full sun to partial shade, and spreads by stolons (above ground stems that produce roots at the leaf nodes). Creeping phlox is relatively free of diseases, with the exception of fungal diseases that affect the foliage.
Brown plant parts with dust-like gray spores are symptoms of botrytis blight, or gray mold, on creeping phlox. The disease usually occurs during cool rainy spring or summer weather.
The fungus, Septoria, causes tan or brown leaf spots, which are usually more severe on older foliage of creeping phlox. Leaf spots usually are usually not harmful to affected plants.
Powdery mildew forms a white or grayish dust on affected leaves during periods of high humidity. Severely affected leaves will wilt and fall off.
Plant creeping phlox where it receives adequate air circulation and drainage to help prevent fungal diseases. Avoid overhead watering, or water in the early morning so that the foliage has time to dry before cool nighttime hours. Remove infected plant parts, clean debris from around plants and destroy to prevent the spread of infection. The use of a fungicide approved for specific diseases on creeping phlox applied according to the manufacturer’s instructions can prevent and control fungal diseases.