Dead Spot on Pachysandras

Leaf Blight

• Most notable of the infestations afflicting pachysandras is leaf blight, also called Volutella blight and stem canker. The blight stems from a fungus (Volutella pachysandrae). Early symptoms of Volutella blight include brownish spots forming on the leaves; these broaden and eventually merge with one another. Such large patches, commonly patterned with concentric bands, can engulf and kill foliage, while dark cankers stud the stems. The fungus reproduces via salmon-colored spore clumps that manifest in spring on the cankers and leaf tissues. Serious infestations can kill the plant and spread easily to neighbors.

Vulnerability

• Highly shade-tolerant, pachysandras excel in shadowed quarters of a yard, and thus homeowners often use them as thick-matted ground cover in such light-starved places. The heavy shade, however, can promote lingering moisture in the soil and on the plants themselves, conditions that could result in leaf-blight outbreaks. The blight often follows some triggering stressor of the plant, such as drought, scale infestation or trimming.

Treatment

• Homeowners can lessen the chances of a leaf-blight infestation by planting pachysandras in well-drained sites or by manipulating the desired location with a raised bed or amendments to the soil. Maintain a healthy spacing between plants by thinning during dry autumn weather, because the fungus thrives with tightly packed host plants. Watering early in the day so plants are dried before sunset mitigates against a wet, humid ground cover patch, as does applying a thinner layer of mulch. Shrubs afflicted with leaf blight should be removed; the Missouri Botanical Garden recommends burying or otherwise disposing of the diseased plants off-site but not composting them to avoid propagating the blight. Fungicides for preventing leaf blight include chlorothalonil and mancozebl; these should be sprayed on the fresh growth of spring and beyond in accordance with the product-specific instructions.

Other Agents

• Other fungal agents that produce dead leaf spots in pachysandra plants include Macrophoma, Septoria, Phyllosticta and Gloeosporium. The resulting diseases, however, tend to be less severe than Volutella blight. Following the same general protocol of selecting appropriate planting sites, proper watering and thinning reduces the incidence of these leaf-spotting afflictions.