Privet plants are shrubs or small trees belonging to the Ligustrum genus. Gardeners of privet may encounter several diseases, most of which can be prevented by providing good air circulation and drainage. Once infected, some privet diseases may require the use of a fungicide and others may require full removal of the shrub and its root system.
Anthracnose attacks weakened privet plants during warm weather and spreads by splashing rain. Tan spots with pink or white spores in the center form on the leaves of infected plants. Cankers may form on branches or twigs. The leaves shrivel and become dry but remain on the shrub. Prune back diseased branches with clean pruning tools and disinfect the tools between each cut. Use rubbing alcohol or a mixture of one part bleach and nine parts water to sterilize your tools. When shoots begin to emerge, apply fungicides to the shrub. Choose resistant cultivars such as Amur, California or Ibota privet.
Cercospora Leaf Spot
The fungal disease Cercospora leaf spot attacks privet during wet weather. Pale yellow spots appear on the leaves. These spots eventually turn brown with reddish brown or purple edges. This disease overwinters on fallen foliage, so regularly clean up fallen leaves and dispose of them away from the garden. Provide significant space between plants to increase air circulation. Avoid watering the foliage or water in the morning to allow time for the leaves to dry. Purchase a fungicide and apply it to both sides of the leaves during wet weather to prevent outbreaks of this disease.
Corynespora Leaf Spot
Small, round, reddish leaf spots appear on plants infected with Corynespora leaf spot. Spots grow in size and turn brown with purple edges. Spots may merge and cause the entire leaf to turn brown and drop from the shrub. Avoid overhead watering and provide air circulation between plants to prevent this disease. Apply fungicides designed to fight leaf spot diseases. This disease attacks Ligustrum sinense, commonly known as Chinese privet. Choose other varieties to avoid Corynespora leaf spot.
Mushroom Root Rot
Mushroom root rot, also known as armillaria root rot, can lead to the death of a privet shrub. Leaves dry out and branches die. If you remove the bark at the base of an infected privet, you will notice a layer of white fungus. Mushrooms may grow in clusters at the base of the plant. Plant privet in well-drained soil to prevent this disease. Remove and dispose of infected plants and surrounding soil.
Wet Root Rot
Wet root rot diseases cause stunted growth and the thinning of foliage. Old leaves turn yellow and the outer layers of the roots begin to decay. Avoid planting privet too deep and plant only in well-drained soil. Check the roots of your privet before planting for signs of this disease. Apply fungicides according to the product's directions to fight wet root rot.