What Is Wrong With My Periwinkle?

Are the leaves curled and yellow?

Are the leaves stippled and distorted?

Do the leaves have white, cottony clusters on them?

Are the leaves and stems covered with small bumps?

Did the shoots blacken and died back to the ground?

Are the flowers discolored and deformed?

Are the leaves spotted or blotched?

Distorted, curled leaves are caused by aphids. These tiny insects can vary in color, green, pink, black, gray to completely white. They cluster under leaves and on growing tips where they feed on plant sap. Leaves, stems, and buds get distorted and later leaves and flowers drop from the plant. You can control them by washing them off the plant with water spray. Insecticidal soap should be used with severe infestations.

Aster leafhoppers are greenish-yellow, tiny insects that feed on leaf undersides, giving the foliage a finely mottled look. Leaves yellow, shrivel and drop. Besides injury from feeding, leafhoppers transmit the disease aster yellows. Use water or insecticidal soap sprays to dislodge nymphs. Encourage enemies such as big-eyed bugs and parasitic wasps. For control of severe infestations, spray plants with neem or pyrethrin.

White, cottony clusters on leaves are caused by mealybugs. These tiny insects are covered with a fluffy white coating. They feed by sucking plants sap. They produce sticky substance honeydew which makes leaves sticky. You can control them by washing them off the plant with water spray. Insecticidal soap should be used with severe infestations.

Leaves covered by small bumps are caused by scales. These tiny, shelled insects often feed on the undersides of the leaves, causing an unhealthy appearance with yellowish blotches on the upper leaf surfaces. Scrape off minor infestations with your fingernail. Prune out badly infested growth, or use a soft brush and soapy water to gently scrub the scales off the stems. Control scales by spraying insecticidal oil during the growing season.

Canker and dieback is a fungal disease that can cause problems for periwinkle. The tips of periwinkle vines turn dark brown or black, wilt, and die back to the soil. The disease is most troublesome during rainy weather. Remove and destroy infected plants or plant parts as soon as you notice them. A spray of Bordeaux mixture may give some control, possibly reducing the spread of the disease to adjacent plants.

Discolored and deformed flowers are caused by Aster yellows disease. This disease is transferred by leafhoppers. There is no cure for Aster yellows, so the affected plants should be destroyed. Prevent the disease by controlling leafhoppers. Spray the plants with the insecticidal soap 3 times, once every 3 days.

Fungal leaf spot diseases thrive on moist leaf surfaces and cause transparent, brown, or black spots that disfigure periwinkle leaves. Flecks or black dots, the spore-bearing fruiting bodies surround some fungal spots. Often spots come together to form larger patches of dead tissue. Dig up and discard seriously infected plants together with the soil surrounding their roots. If the leaf spot is a problem, water periwinkle with a drip irrigation system to avoid wetting the foliage. Spray at weekly to 10-day intervals with a flowable sulfur spray.

Dog urine is a problem with groundcovers. It may discolor and kill the foliage. Spraying the foliage of endangered periwinkle with an anti-transpirant gives some protection. Try an aerosol pet repellent.