Pachysandra is another popular ground cover that has exhibited disease problems. The wet weather of spring and early summer has encouraged development of many diseases on low-lying plants.
Pachysandra blight is caused by the fungus Volutella pachysandrae. The disease begins as brown leaf blotches that develop targetlike rings. The fungus may progress through stems and stolons, causing cankers that girdle and kill stems. Look for wilted pachysandra plants with brown blotches on the leaves. Push back the leaves to find the blotches and cankers on stems. An easy-to-spot diagnostic feature is pink-to-orange spore masses on the underside of leaves or on stems. Spore masses are common in moist weather. Look particularly for Volutella blight in dense plantings where thick mulch has been used and conditions are warm and moist. The disease often follows stress, such as winter injury, insect infestation, sunscald, or recent shearing. Remove and destroy any severely infected plants. Do this when plants are dry to prevent further disease spread.
Because this disease is more likely following injury or stress, try to provide a protected location for pachysandra. This species thrives in shade in a moist, well-drained, acidic soil with plenty of organic matter. Remove dead or diseased plant material and concentrate on improving site conditions. Chemicals may be used as protectants, with repeat applications at 10- to 14-day intervals, depending on the product and weather. Copper, mancozeb, and chlorothalonil are some active ingredients registered for this use on pachysandra. Look in the Home, Yard, and Garden Pest Guide and the Illinois Commercial Landscape and Turfgrass Pest Management Handbook for specific products. Effective nonchemical controls include keeping insects under control and mulching pachysandra with a material that does not hold excessive moisture. Pruning any surrounding plants for better air movement in the area may also help manage this fungus. Consult Report on Plant Disease, no. 649, for more information.