Ligustrum, or privet, is a vigorously growing evergreen with several variations, including the Japanese privet, Chinese privet, California privet and the glossy privet. These relatively low-growing trees produce dense, richly coloured foliage that makes Ligustrum trees ideal for landscaping borders and hedges.
Anthracnose is a blighting disease that targets the Ligustrum tree's newly developing shoots and foliage. The fungal spores lie dormant within the crevices of the tree and emerge during the rainy days of the early spring. The Ligustrum tree's young foliage becomes curled and distorted, and develops small, dark coloured spots that turn into enlarged, sunken lesions. Some of the shoots may die before emergence. Severely infected trees may experience defoliation, and develop cankers on twigs and branches.
Powdery mildew is a common fungal disease that is most aggressive during the late summer and early fall months. This mildewing disease infects the foliage surfaces with coverings of powdery white fungus. Though mostly a cosmetic disease, severe powdery mildew infections can cause the Ligustrum tree's foliage to become distorted and weaken the overall health of the tree.
Ligustrum trees infected with phymatotrichum root rot have little chance for survival. This soil-borne fungal disease infects the Ligustrum through its root system. The severity of the disease is promoted by the Ligustrum's rapid growth. This root rot causes the breakdown of the tree's vascular system, which prevents the transport of nutrients and water throughout the tree. The infected tree experiences browning and wilting of the foliage, dieback and growth stunt. Ligustrum trees infected by phymatotrichum root rot should be removed and discarded.
Most of the Ligustrum's infectious predators can be avoided with general maintenance and preventive steps. Always keep the privet's planting area free of debris, as this will eliminate many of the area's fungal spores. Treat the privet regularly throughout the growing season with a fungicidal spray to reduce the potential for infections.