Pachysandra Leaf and Stem Blight

Leaf and stem blight, a destructive disease of pachysandra, is caused by the fungus Volutella pachysandrae. Both the leaves and stems of pachysandra are attacked by this fungus. Brown blotches on the leaves are usually the first noticeable symptoms. The blotches gradually increase in size until the entire leaf turns brown or black and dies.
In severe infections, stem cankers (browning of the stem at the terminal, mid-stem or ground level) occur and will cause the plant to wither, turn brown or black and die. During wet weather, affected parts are often covered by pink masses of fungus spores. Further spread of the disease throughout the planting is by means of these spores. Plants die in patches, and the disease commonly produces a circular pattern in the bed.

Disease spread is most rapid in dense overcrowded plantings and in plantings weakened by drought, winter injury or attacks by insects. Use of a damp, heavy mulch which provides excessive moisture also encourages disease development.

Rogue and destroy all severely diseased plants. Thin thick plantings to increase light and air circulation. Remaining plants may be protected with a fungicide such as chlorothalonil (Bravo, Daconil 2787) or mancozeb Dithane, Penncozeb). Spray the plants two or three times at 10 to 14 day intervals. If volutella blight has been a problem in the past, it may be necessary to protect plants with two or three fungicide applications beginning when new growth starts each year.

Avoid heavy, thick mulches of materials, such as leaves or compost which hold moisture and favor the establishment of the disease.

Since the disease spreads rapidly in stands that have been weakened by insects, make an attempt to control them. Scale insects, particularly euonymus scale, can be very destructive. For control of scale, prune badly infested plants. Spray with an insecticide such as malathion, carbaryl (Sevin) or acephate (Orthene) during the first week of June and repeat in early July.

A horticultural oil can be applied in mid-April to early May. If coverage is good, excellent control can be achieved.

Prepared by: David B. Schroeder, Extension Plant Pathologist,
Edmond L Marrotte, Consumer Horticulturist

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