Common or European privet (Ligustrum vulgare) and Chinese privet (L. sinense) have escaped into the wild in South Carolina to become weedy and invasive pests. Birds eat the small, black fruit and deposit the seeds everywhere. Many other Ligustrum species, however, are more well-mannered landscape plants, but still may spread by seed dispersal. Privets are most often grown as hedge plants because they are so easy to grow. All have abundant, showy clusters of very sweet smelling, white flowers in late spring. Clipped hedges bear fewer flowers, since shearing removes most of the flower-bearing branches.
Japanese Privet (Ligustrum japonicum)
Mature Height/Spread: This is an evergreen shrub with a compact growth habit to 10 feet high and 5 to 6 feet wide. The foliage is 2 to 4 inches long and rather leathery. The oval leaves are glossy green above and almost white beneath. The white flowers appear in May and have a very strong odor, which may be offensive to some people. The blue-black berries mature in September to October and often persist through the winter. They are about ¼ inch in diameter. Birds do not seem to be interested in these berries.
Growth Rate: Japanese privet has a rapid growth rate of 25 inches or more per year.
Landscape Use: This shrub is excellent for use as a hedge or screen or for shaping into a small tree.
Cultivation: Japanese privet is adapted to adverse conditions of drought, heat, cold, many soil types and salt spray. It is easily transplanted and prefers partial shade to full sun. The only soils this shrub does not grow in well are those that are permanently wet.
Cultivars & Varieties:
- ‘Rotundifolium’ or roundleaf Japanese privet grows to 5 feet and has nearly round leaves to 2½ inches long.
- ‘Howard’ has leaves that are yellow when new and green when mature. Both colors are present at the same time.
- ‘Recurvifolium’ is a slightly smaller-leaved form with wavy leaf margins. The leaves are twisted at the tip.
- ‘Silver Star’ grows to 8 feet and has leaves that have gray-green mottling and silver edges.
- ‘Variegatum’ has leaves with white margins and blotches.
Glossy Privet (Ligustrum lucidum)
Mature Height/Spread: This evergreen tree will reach 35 to 40 feet, but can be kept lower as a big shrub. The spread is about 5 to 10 feet. The leaves are 4 to 6 inches long, glossy dark green on both sides and less spongy than the leaves of Japanese privet. Glossy privet has large clusters of white flowers, followed by many purple-blue berries.
Growth Rate: The growth rate is very rapid.
Landscape Use: Glossy privet makes a fine lawn tree and is excellent as a tall screen or windbreak. There are some disadvantages to planting this tree. The fruit crop is immense and berries will drop on and stain paved areas and cars. Fallen berries sprout in groundcover and will need pulling. Many people dislike the flower smell and fruiting clusters are bare and unattractive after fruit drop.
Cultivars & Varieties:
- ‘Compactum’ has dense, dark green, waxy leaves.
- ‘Davidson Hardy’ is an exceptionally hardy plant with excellent foliage.
- ‘Tricolor’ has leaves that are variegated with white, and they are pink when young.
- ‘Macrophyllum’ has very large leaves.
California Privet (Ligustrum ovalifolium)
Mature Height/Spread: This semi-evergreen shrub grows rapidly to 15 feet, has dark green, 2½-inch leaves and dull white, heavy scented flowers.
Landscape Use: California privet makes a good hedge, when plants are set 9 to 12 inches apart. The hedge requires frequent shearing, especially in hot, wet weather. Seedlings come up everywhere and established plants are hard to get rid of.
Cultivars & Varieties:
- ‘Argenteum’ has leaves that are bordered with creamy-white.
- ‘Aureum’ has leaves with a green spot in the center and bordered with golden yellow. This variety is also sold as ‘Variegatum’ or golden privet.
Mature Height/Spread: This semi-evergreen shrub grows quickly to 4 to 6 feet with an equal spread. It has gray-green leaves with white margins, which makes it a popular shrub for brightening dull areas of the garden. This shrub may revert to the species, which has dull, grayish leaves. These odd branches need to be pruned out.
Vicary Golden Privet (Ligustrum vicaryi)
Mature Height/Spread: This deciduous shrub grows to 6 feet, sometimes to 12 feet. The leaves are golden yellow. This color is strongest on plants in full sun and does not develop well under hedge shearing.
Chinese Privet (Ligustrum sinense)
Chinese privet is an aggressive and troublesome shrub and listed by the SC Exotic Pest Plant Council as a “severe threat” in South Carolina. This exotic shrub is notorious for producing dense thickets, especially in bottomland forests and in floodplains, where these thickets choke out all native plants. Chinese privet spreads both by root sprouts arising from rhizomes and by abundant seed production. Birds eat and disperse the blue-black fruit during winter. In floodplains, seeds also are spread by floodwaters.
Variegated Chinese privet (Ligustrum sinense ‘Variegata’) is an ornamental shrub commonly offered for sale, which has attractive yellow variegation along the margins of its small leaves. This variegated form of Chinese privet does produce flowers and fruit. These shrubs tend to revert back to having solid green foliage on portions of plants, and if these sections are not pruned out, they will over-take the variegated sections because of their more rapid growth. These solid green portions of Chinese privet then produce abundant fruit, which are eaten and dispersed by birds or spread by surface water. Therefore, it is highly recommended to not plant variegated Chinese privet because of this potential for rapid spread and displacement of native flora.
Fungal Leaf Spots: Leaf spots caused by the fungi Cercospora species and Pseudocercospora species appear as angular to irregular-shaped, tan sunken lesions with purple margins. Frequently chlorosis (yellowing) occurs on the leaf areas surrounding the leaf spots. Spots may begin small, but enlarge or merge. These leaf spots are fairly common on Ligustrum foliage; however, these foliar diseases are not usually serious. Fungal leaf spots typically occur during warm, moist summer months, and initially will occur on older foliage.
Prevention & Control: Many foliar problems can be prevented by keeping leaves as dry as possible. Avoid overhead irrigation and improve air circulation with adequate plant spacing and selective branch pruning. Prune overhanging trees around diseased shrubs to reduce humidity levels and speed the drying of foliage. Hand remove spotted leaves on lightly diseased plants. Rake up and destroy infected fallen leaves. The removal of this leaf material will minimize the chances of the disease reoccurring the next season. Mulch beneath shrubs to aid in disease reduction. Irrigate shrubs by drip irrigation or by soaker hoses.
If chemical control is needed, most fungal leaf spots can be controlled with sprays of fungicides containing chlorothalonil, thiophanate-methyl, myclobutanil, or mancozeb (see Table 1 for specific products). Apply when symptoms first appear and repeat every 10 to 14 days as needed.
Botryosphaeria Dieback & Canker: The fungal disease called Botryosphaeria dieback and canker, caused by Botryosphaeria species, is most likely to occur on plants suffering from drought stress, bark injuries, pruning wounds, or other environmental stresses. Healthy plants are much more resistant to infection by Botryosphaeria, as they will wall off the fungus and prevent its spread through the branch.
Upon entry via a wound, the fungus kills cambium and sapwood tissue, causing sunken dead areas called cankers. The cankers are small initially, but enlarge or coalesce (merge) into large areas that girdle the branch or trunk. Water movement is stopped beyond that point and results in a rapid wilting or browning of foliage. Branches with cankers may fail to leaf out in the spring.
Prevention & Control: Water shrubs weekly during the growing season if insufficient rainfall occurs (see HGIC 1056, Watering Shrubs & Trees). Mulching shrubs helps to avoid mechanical injury to trunk and limbs by weed trimmers and lawn mowers. Mulch shrubs with a 2- to 4-inch layer of bark, pine needles or ground leaves, and avoid piling the mulch against the trunk.
Prune any branches with cankers back to green healthy wood. If entire branches must be pruned, cut the limb just outside the branch collar and not flush with the trunk. Disinfest pruners between every cut with a 70% alcohol or 10% bleach solution. Dispose of all prunings, as this plant material is a potential source of disease for Ligustrum species, as well as other woody shrubs. No fungicides are recommended for the control of fungal cankers, but pruning wounds may be sprayed for protection with a fungicide, such as thiophanate methyl (see Table 1 for specific products).
Armillaria Root Rot: Armillaria root rot is also known as shoestring root rot, mushroom root rot, and oak root rot. It is caused by the fungus Armillaria mellea, which is common in landscape and garden settings. This fungus can rot the roots of many different kinds of plants. Most often this disease is found on trees and shrubs such as oak, pine, rhododendron, and dogwood, but hundreds of plant species, including Ligustrum species, are susceptible. Typically, the symptoms of this root rot occur over the whole plant. Aboveground parts of the shrub generally appear stunted and yellowed, and leaves may drop. The unhealthy foliage may become sparser over a period of several years. However, there may be no evidence of any problems, and suddenly the shrub will die. The cause of the unhealthiness or death may be difficult to determine, as similar symptoms may be caused by environmental factors, such as weather stress or a general lack of plant care.
Armillaria root rot can be distinguished from other root rots, or from drought or excess moisture injury, by examining the crown (lower trunk) and upper roots of the plant. If Armillaria is responsible for the plants decline, and if the bark is carefully peeled back, a white felt-like fungal growth can be seen under the bark. If sufficient bark is removed, the leading edge of the fungal growth will be found, and this white growth has a characteristic fan-shape. The Armillaria root rot fungus also forms black, string-like fungal strands about 1/16-inch in diameter or less. These strands may often be seen between the bark and the wood, or on the surface of the roots, or in the nearby soil. These string-like fungal strands are called shoestrings and look very similar to roots.
Prevention & Control: Provide good growing conditions for the Ligustrum species, especially additional water during droughts, good soil drainage, and proper fertilization.
An infected shrub whose entire root system or trunk is diseased cannot be saved. When a shrub dies from Armillaria root rot, the large roots in the vicinity of the trunk, as well as the trunk itself, should be removed and destroyed. Soil in the immediate vicinity also should be removed. Avoid replanting the same species as the one removed.
Whiteflies: Whiteflies are not true flies, but are more closely related to scale insects, mealybugs and aphids. They are very small – about 1/10 to 1/16 inch long. They have a powdery white appearance and resemble tiny moths. When at rest, the wings are held at an angle, roof-like over the body. The immature stage is scale-like and does not move. When plants that are infested with whiteflies are disturbed, the whiteflies flutter around briefly before settling again.
Both adults and immature forms of the citrus whitefly (Dialeurodes citri) feed by sucking plant sap. The damage that they cause is similar to that caused by aphids. The infested plant may be stunted. Leaves turn yellow and die. Like aphids, whiteflies excrete honeydew, which makes leaves shiny and sticky and encourages the growth of sooty mold fungi.
Control: Insecticidal soap or horticultural oil sprays are effective against whiteflies, but the plant must be sprayed thoroughly so that the soap or oil contacts the insects on the underside of leaves. Repeat spray three times at 5 to 7 day intervals. Foliar injury from soaps and oils may occur on plants under drought stress. Therefore, water the plants well the day before spraying. Only apply horticultural oils or insecticidal soaps if temperatures are below 90 °F, and apply very late in the day to prevent foliar injury. If stronger insecticides become necessary, products containing bifenthrin, cyfluthrin, permethrin, esfenvalerate, acephate, and imidacloprid can be used. Acephate is a foliar systemic insecticide and may provide better control than the other contact insecticides. Spray Ligustrum shrubs at 10 to 14 day intervals, as needed. Soil-applied insecticides, such as imidacloprid, can give season-long control of whiteflies. These are applied as a soil drench or as granules, which are watered into the soil. See Table 1 for products that contain these insecticides.
Root Rots: Various pathogens, including Phytophthora and Pythium, cause root rots in Ligustrum species. In South Carolina, Phytophthora is identified most often as the pathogen. As the disease name indicates, root rots are characterized by a decay of some portion of the roots.
Aboveground symptoms of root rot include leaf yellowing (oldest leaves first), leaf drop and wilting. Depending on how extensively the roots are affected as well as which roots are affected, the plant may appear generally unhealthy for an extended period of time, or wilt suddenly and die. In addition, the symptoms may be present on only one side of the plant or may affect the plant as a whole.
When aboveground symptoms indicate root rot, roots should be examined as soon as possible. A healthy root system will have white feeder (non-woody) roots present. With root rots, the feeder roots may be brown and rotting, or missing completely. The outer tissue (cortex) of rotting roots can be easily removed by pulling, leaving behind the threadlike core or stele (conducting tissue).
Disease development is favored by any factor that encourages wet soil conditions, including poor drainage and over irrigation. Planting too deeply also contributes to the problem.
Control: The best management practice for root rot problems is prevention. Check the roots of nursery stock before purchasing. Make sure there is adequate drainage in the area where you want to plant. If the area drains poorly, creating a raised bed can help.
If a plant has already died from Phytophthora root rot and a replacement is wanted for the same location in the landscape, it is best to choose a plant that is known to have resistance.
Table 1. Insecticides and Fungicides for Insect Pest and Disease Control on Ligustrum species.
|Active Ingredient||Brand Names and Products|
|Acephate||Bonide Systemic Insect Control Concentrate|
|Bifenthrin||Bifen I/T Concentrate
Ferti-lome Broad Spectrum Insecticide Concentrate
Hi-Yield Bug Blaster Bifen 2.4 Concentrate
Ortho Bug-B-Gon MAX Insect Killer for Lawns & Gardens Concentrate
TalStar P Concentrate
UpStar Gold Insecticide Concentrate
|Chlorothalonil||Bonide Fung-onil Multi-purpose Fungicide Concentrate
Ferti-lome Broad Spectrum Landscape & Garden Insecticide
GardenTech Daconil Fungicide Concentrate
Hi-Yield Vegetable, Flower, Fruit & Ornamental Fungicide Concentrate
Ortho Max Garden Disease Control Concentrate
Southern Ag Liquid Ornamental & Vegetable Fungicide
Tiger Brand Daconil
|Cyfluthrin||Bayer BioAdvanced Complete Insect Killer for Soil & Turf I RTS1
Bayer BioAdvanced Insect Killer for Lawns RTS
|Horticultural oil||Bonide All Seasons Spray Oil Concentrate
Ferti-lome Horticulture Spray Concentrate
Monterey Horticultural Oil Concentrate
Southern Ag ParaFine Horticulture Oil Concentrate
Summit Year Round Spray Oil Concentrate
|Imidacloprid||Bayer Advanced Garden Tree & Shrub Insect Control Concentrate (drench)
Bonide Annual Tree & Shrub Insect Control w/ Systemaxx (drench)
Ferti-lome Tree & Shrub Systemic Insect DrenchHi-Yield Systemic Insect Spray (drench)
Martins Dominion Tree & Shrub (drench)
Monterey Once A Year Insect Control II (drench)
|Insecticidal soap||Natural Guard Insecticidal Soap Concentrate
Safer Brand Insect Killing Soap Concentrate
|Lambda cyhalothrin||Martin’s Cyonara Lawn & Garden Concentrate; & RTS1
Spectracide Triazicide Insect Killer for Lawns & Landscapes Concentrate (also in RTS1)
|Mancozeb||Bonide Mancozeb Flowable with Zinc Concentrate
Southern Ag Dithane M-45
|Myclobutanil||Ferti-lome F-Stop Lawn & Garden Fungicide Concentrate; & RTS1
Spectracide Immunox Multi-Purpose Fungicide Concentrate
|Permethrin||Bonide Eight Insect Control Vegetable, Fruit & Flower Concentrate
Bonide Eight Yard & Garden RTS1
Hi-Yield Indoor/Outdoor Broad Use Insecticide Concentrate
Southern Ag Permetrol Lawn & Garden Insecticide Conc.
Tiger Brand Super 10 Concentrate
|Thiophanate-methyl||Cleary’s 3336 Turf & Ornamental Fungicide
Southern Ag Thiomyl Systemic Fungicide
|1RTS = Ready to Spray (hose-end applicator)
Drench = Add to water and pour around base of plant.
Note: As with all pesticides, read and follow all label instructions and precautions.