Informational table showing disease name, symptoms, pathogen/cause, and management of Boxwood diseases. Disease Symptoms Pathogen/Cause Management Decline Stunted growth and dieback occur. Young foliage turns grayish green or bronze and finally straw colored. Old leaves fall prematurely. Middle or top branches die. Sunken cankers form at the soil line or on branches in the crotches where dead leaves accumulate. Wood under the sunken canker is blackened. Attack by various fungi and nematodes add to damage from winter injury and stress on plants, especially those in poorly drained sites. Protect plants from winter injury and other stresses. Prune dead branches well below cankered areas. Remove dead leaves accumulated among the branches. Blight Leaves on the lower part of the shrub have brown spots. Leaves may turn straw-yellow or bronze and fall. Twigs have long brown lesions. Under wet conditions, white fungal growth is observed on the leaves and twig lesions. Young plants in propagation are killed. Neonectria pseudonaviculatum (asexual stage, Cylindrocladium pseudonavitulatum. Formerly known as Cylindrocladium buxicola) Buxus sempervirens, B. microphylla (littleleaf boxwood) and var. japonica (Japanese boxwood), B. sinica var. insularis (Korean boxwood), B colchica and Pachysandra are susceptible. Long distance spread of the pathogen is through the movement of infected nursery material. Remove and destroy severely affected plants. Do not try to compost leaves from infected plants. The sticky spores of the pathogen are readily spread from plant to plant on tools and contaminated clothing and gloves. Thin boxwoods to obtain good air circulation among the branches. Apply a fungicide in a manner that achieves through coverage of the top and bottom of leaves and twigs. Leaf burn Leaf tips and margins yellow and redden as leaves fall prematurely. Water stress and low temperature. Protect shrubs from drought and drying winds in the autumn and winter. Leaf spot Straw-yellow leaves are dotted with small, black fungal fruiting structures. Macrophoma candollei Only leaves weakened by winter injury are infected. Protect plants from wind, salt spray, and salt runoff. Nematodes Growth is stunted, leaves have a bronzed appearance, and the shrub is in decline. Small roots have small brown dead areas which enlarge to engulf the entire root ends. Pratylenchus There are no adequate controls once the plant is infected. If a plant is removed, do not replace it with a nematode-susceptible plant unless the site is thoroughly fumigated and aerated first. Volutella blight Leaves on branch tips turn tan, straw-yellow or bronze color in the spring as they die. Under wet conditions, foliage may have masses of pink to salmon colored spores on them. Dead branches have loose bark. Volutella buxii (asexual stage of Pseudonectria rouselliana) During dry weather, prune dead branches and prune to thin the plant so that there is good air circulation within the canopy. Remove all dead leaves and fallen leaves from around the plant. Apply a fungicide to protect new growth in the spring and in the fall. Spray to obtain very thorough coverage of leaves and twigs.

Prepared by Gary W. Moorman, Professor of Plant Pathology