Volutella Blight of Pachysandra
By Dr. Sharon M. Douglas
Department of Plant Pathology and Ecology
The Connecticut Agricultural Experiment Station
123 Huntington Street
P. O. Box 1106
New Haven, CT 06504-1106
Telephone: (203) 974-8601 Fax: (203) 974-8502
SYMPTOMS AND DISEASE DEVELOPMENT:
Leaf and stem blight is the most destructive disease of pachysandra in the Northeast. It is caused by the fungus Volutella pachysandrae. Patches of wilting and dying plants often indicate the presence of Volutella blight in a bed of pachysandra. Both leaves and stems are attacked by this fungus. Leaves develop irregular tan to brown blotches, often with concentric lighter and darker zones with dark-brown margins. These blotches gradually increase in size until the entire leaf turns brown or black and dies.
Stem cankers often develop and cause whole plants to die back. These appear as a browning of the stem at the terminal, midstem, or at ground level. Cankers first appear greenish-brown and water-soaked, but eventually turn brown or black and shrivel. As these cankers girdle the stem, they cause the whole plant to wither and die. During wet, humid weather in late spring and summer, affected plant parts can be covered with reddish-orange, cushion-like fruiting structures of the fungus. Spread of the disease within the planting is by means of these fungal spores. Plants often die in patches and the disease commonly produces circular patterns in the bed. Volutella blight is more severe in plantings weakened by winter injury, insect infestation, recent transplanting or shearing, drought, and exposure to full sun.
Control can be accomplished by following a multifaceted approach that includes sanitary, cultural, and chemical controls. All plant debris and severely disease plants should be removed and destroyed. The planting should be thinned periodically to prevent dense growth and increase light and air circulation. Among the fungicides registered for use are thiophanate methyl, chlorothalonil, and mancozeb. Plants should be sprayed when new growth starts in the spring and repeated according to label directions to protect newly emerging tissues. Additional applications may be necessary during wet weather. The pesticide label will contain information on dosage rates and safety precautions. Since Volutella blight is associated with plant stress, attempts should be made to control insect infestations and to maintain good growth and vigor by watering during periods of drought and fertilizing in the spring. Since water favors disease development, watering is best done early in the day so that drying occurs. Thick, heavy mulches should be avoided since they hold moisture. It is also important to remove any leaf or plant debris from the bed before growth resumes in early spring.
Volutella blight is the most destructive disease of pachysandra in Connecticut and the Northeast. This disease is caused by the fungus Volutella pachysandrae. Symptoms can vary from irregular, tan to brown blotches with concentric-ring patterns on the leaves to stem cankers that result in extensive wilting and death of large patches of plants within a planting bed. In addition to descriptions of these symptoms, this fact sheet includes a discussion on strategies to minimize the impact of this common disease.