Pachysandra (Pachysandra terminalis), a popular low-growing ground cover, rarely grows more than 10 inches in height and maintains its striking evergreen appearance throughout the year. Often grown in full or partial shade, the plant requires moist, acidic soil conditions to thrive. A lush ground cover, it is easily established within three years. Unfortunately, the pachysandra often suffers from several problems that can result in the death of the plant if left untreated.
Volutella blight, also known as leaf blight, is a fungal infection caused from the fungus Volutella pachysandra. The affliction produces irregular black and brown spots on the leaves and stems.The spots appear in a bulls-eye fashion of black and tan rings. In the early spring, when the disease first erupts, the leaves of the pachysandra appears slightly pink with the new fungal spores. Once the spores begin to mature, the disease gives all the foliage of the plant an orange cast that almost appears as if the plant has been lightly dusted in orange powder. As the fungal disease progresses, the plant begins to thin out and die.
Control volutella blight by creating air circulation around the pachysandra. Remove all infected foliage and promptly discard. Weed around the plants to promote air flow. Keep the foliage of the plant dry and water using flood irrigation only. Once air is allowed to reach the plant's foliage and the leaves dry out a little, the fungal infection normally dissipates.
Euonymus scales (Unaspis euonymi) are a common problem on pachysandra. The female insects lay eggs in May. The larvae emerge and begin feeding on the sap of the plant. They produce a scale over their tiny bodies that appears as white or brown flecks on the stem and leaves of the plant. The females tend to enjoy feeding on the sap from the stem of the plant, but the males will form scales on the plant's leaves. A heavy infestation will cause the pachysandra to rapidly loose its leaves. The upper portions of the leaves often appear to be a mottled yellow and the underside of the leaves will be dotted with the male scales. The scales normally produce two egg cycles in a season.
Mow the pachysandra completely to the ground and let it regrow on its stolons if the infestation is severe. Apply foliar insecticides such as carbayl or acephate to gain control. Follow the directions on the label for application. Using ultrafine horticultural oil in the spring will help prevent infestation.
The leaves of the pachysandra are prone to scorch. This condition causes the leaf margins to appear brown and papery, deteriorating the overall appearance of the plant. The cause of the problem is believed to be drying winter winds with lack of a protective snow cover. The problem can often be prevented by raking leaves over the pachysandra or applying another lightweight mulch. New growth on the plant will rarely be affected once the temperatures return to normal and spring arrives.
The oystershell scale (Lepidosaphes ulmi) enjoys sucking the sap from the pachysandra. The insect attaches to the stems and underside of the leaves. The scale that forms over the insect has the general appearance of an oyster shell. The females lay eggs that emerge as crawlers. Crawlers appear to be tiny pink specks on the plant's surface. The crawlers quickly take up residence and begin to consume the sap of the plant while forming a protective scale. The plants foliage begins to wilt and die with an infestation.
Control the oystershell scale by using ultrafine oil, malathion or insecticidal soap. Follow the directions on the label for application.