What Can Attack Ligustrum?

Drowning and Edema

• Drowning and edema problems occur in water retentive sites. With drowning, the saturated roots malfunction and begin to die. As the roots slowly die, the foliage wilts and becomes discolored. Eventually, the leaves die and drop from the plant, leading to the ligustrum's death. Fusarium and verticillium wilt fungi then infect the root system. Both fungi kill ligustrums, as there is no cure, according to the University of Illinois Extension. Edema shows up on ligustrum foliage as small bumps. When ruptured, the bumps become a brownish-tan color. Edema is usually not life-threatening, unlike drowning. Control the infections by growing ligustrums in well-drained soils or raised beds and not overwatering.

Botrytis

• Botrytis is a fungal disease occurring in wet, humid conditions. It survives on live or dead portions of plants and spreads through wind or watering. It is most prevalent when temperatures range between 32 to 84 degrees Fahrenheit, according to the University of Illinois Extension. Symptoms include grayish moldy foliage, leaf curl, leaf drop and wilting. Branches also suffer dieback. The fungus sometimes kills ligustrum plants, though the process may take a year or more. To control the infection, rake up dead foliage and prune away infected portions of the plant. Discard the diseased material inside plastic bags, burn it, or bury it 1 to 2 feet deep into the soil. Reduce infection by avoiding overhead watering systems and allowing proper air circulation. Spray infected plants with a fungicide safe for use on ligustrums, following label instructions.

Uglynest Caterpillars

• Uglynest caterpillars are moth larvae using ligustrums as host plants. Caterpillars have a black head and greenish-yellow bodies. The nest is a combination of foliage and branches. Caterpillar damage is aesthetic and not life-threatening to the plant. Nest development occurs springtime throughout summer. The orange, adult moths emerge in midsummer through early autumn. To control the infestation, gardeners can crush the nest with their hands. Spraying the nest with insecticide also kills the caterpillars. Use an insecticide safe for use on ligustrums, following product instructions. Saturate the nest with the product, thoroughly penetrating the web.

Sucking Insects

• Aphids, thrips, scale, spider mites and whiteflies suck the juices from ligustrums. Privet thrips feed on the plant's flowers. Aphids attack new foliage causing leaf curl. Scales attach to the plant's foliage and stems, generally remaining in one place. Whitefly infestations are noticeable, as the insects fly around moved plants. The insects are most prevalent in spring, summer or early fall. Spider mite infestations develop rapidly, with the insects attacking foliage undersides. Infected foliage has a rusty discoloration. Treat spider mites with two miticide applications one week apart, according to the University of Florida IFAS Extension. Treat aphid, scale, thrip and whitefly infestations with an insecticide safe for use on ligustrums. Follow the product's application instructions.