Black-Eyed Susan Vine Pests

The black-eyed Susan vine is not related to the daisylike black-eyed Susan, Rudbekia hirta.

In its native Africa, the black-eyed Susan vine (Thunbergia alata) is a sun-loving perennial that can reach heights of 20 feet. Most gardeners in the United States grow it as an annual, however, starting the vine from seed each spring. Whiteflies, scales and spider mites are the pests most likely to plague the petals of this pretty flowering vine.

Whiteflies

Seemingly ubiquitous, these tiny, white, mothlike flies take flight in large groups when disturbed. They are usually found on the undersides of leaves where they use piercing mouthparts to suck sap. A fine, white stippling is the most common symptom of whitefly feeding. They can also cause wilting and death in large populations. Whiteflies are difficult to control, but regular applications of insecticidal soap or horticultural oil can help. Spray in the morning before their wings have warmed for flight and target the spray at the undersides of leaves.

Scales

These immobile, brown lumps of pest look like scabs and are typically found on stems and petioles. Scales are sap-feeding pests protected by a round, domed shell. While the adults are immobile, newly hatched scales can move freely and are called "crawlers." Crawlers wander around the plant until they find an adequate feeding site where they will latch on with their mouthparts and stay for the rest of their lives. As they age they develop their protective shell. Focus control efforts on the crawlers, as adults are well protected from insecticides. Spray insecticidal soap or horticultural oil at 10-day intervals beginning in May and throughout the summer.

Spider Mites

These pests are not insects but are actually related to spiders. They use piercing mouthparts to suck sap from leaves, stems and flowers. Spider mites are microscopic and can be difficult to see, but they leave a fine webbing stretched all over the vine as they move and feed. Spider mite feeding damage generally causes yellowing or bronzing of leaves. These pests thrive in dusty conditions. Use a strong jet of water to wash pests and dust from your vine. Regularly wash the plant with water and wet down any dirt paths near it.

Honeydew

Sap-feeding pests like whiteflies, spider mites and scales excrete a sticky, sweet substance called honeydew. Dirt, dead plant matter, dead insects and other debris can become stuck in honeydew and leave your vine looking messy. Honeydew also attracts a fungus called sooty mold. This powdery black mold feeds on the honeydew, coating leaves, stems and flowers. Sooty mold does not feed on the plant directly but it can shade it out, preventing photosynthesis. The surest way to rid plants of sooty mold is to control the pests leaving behind honeydew.

References

• University of Arkansas; Black-Eyed Susan Vine; Gerald Klingman; August 2006
• Fine Gardening: Thunbergia Alata (Black-Eyed Susan Vine)
• Virginia Cooperative Extension; Whiteflies; Kenneth W. Cote et al.; May 2009
• Virginia Cooperative Extension; Scale Insects; Eric Day; May 2009
• Ohio State University Extension; Spider Mites and Their Control; David J. Shetlar