Pachysandra is susceptible to leaf blight--also referred to as Volutella blight or dieback. Leaf blight is a fungal disease caused by the Volutella pachysandricola fungus. Overcrowded beds are generally affected. This fungal disease can kill large areas of a pachysandra groundcover bed. It generally attacks weak or injured plant
Pachysandra (Pachysandra terminalis, a member of the Buxaceae–Box--family) is also commonly known as Japanese Pachysandra or Japanese Spurge. It is an herbaceous perennial evergreen groundcover of medium size. Pachysandra’s growth habit is mat-like, and slow growing. It reaches approximately 10 inches in height, and spreads by basal shoots. It is hardy in zones 5 to 8.
Site Selection is Important in Preventing Disease
Site selection is important to the health of the plants. Pachysandra does well in organically rich, well-drained acidic soil--it will tolerate soil that has a pH that is neutral/slightly alkaline as long as it drains well. Leaf blight thrives in wet soil conditions--especially at sites that are not well-drained. Also, plants require a site that receives partial to deep shade (prefers full shade). They become stressed when they receive too much sunlight. Since maintaining the health and vigor of the pachysandra is the best defense against disease, use care in selecting a site that fills the pachysandra's key needs.
Leaf blight of the pachysandra plant is a fungal disease caused by the Volutella pachysandricola fungus. It is a devastating disease that can destroy large areas of a pachysandra bed. The first sign of this fungal disease is the appearance of tan to brown (with darker brown margins) blotches on the infected leaves. These blotches then become larger, and cankers can be seen around the stems and runners of the plant. As the disease progresses, the plants wilt and then die. This disease usually occurs under warm, wet and humid conditions (late spring and summer).
Plants That are More Susceptible
Plants that are stressed/weak or injured are more susceptible to leaf blight; therefore, it is important to monitor and provide necessary corrective measures to maintain a healthy groundcover bed (healthy plant tissue is better able to fight off disease). Pachysandra can become stressed when it has been injured during the winter season (by de-icing salt or winter winds), during a drought, when it receives too much sunlight or when it has been infested by insects. Other factors that encourage leaf blight are: very dense growth, which limits air circulation, and heavy mulch application, which limits drainage. These factors promote conditions conducive to leaf blight.
Keeping Pachysandra Healthy
To keep a pachysandra bed healthy, attend to potential problems as soon as you see them. Thin out pachysandra when the bed becomes dense to improve air circulation. Be sure to remove any debris from the groundcover bed, such as fallen branches or leaves--debris inhibits the air from circulating between the plants. Be careful not to apply de-icing salt near pachysandra plants in the winter season, as this may cause injury. Control any insect infestations as soon as possible, as they also weaken plants. Follow a regular program of fertilization to promote vigorous growth.
Controlling the Disease.
If your plants do become infected, prune out and destroy the infected plants. (Be sure to disinfect your pruning shears so that you do not spread the disease.) Spray the remaining plants with a fungicide. The University of Connecticut recommends using such fungicides as: chlorothalonil (Bravo, Daconil 2787) or mancozeb (Dithane, Penncozeb). And they recommend that plants be sprayed 2 to 3 times at 10- to 14-day intervals.