Questions From Our Help Desk

Cherry Laurel Scale

This looks like scale on my skip laurel bushes, limiting their growth and causing them to appear less plush than my other shrubs. I treated them 45 days ago with a soil drench recommended by a local garden center but it doesn’t appear to be doing any good. What can I do?
– Jason / September 2025

Skip laurels are a cultivar of cherry laurels (Prunus laurocerasus) which are a popular landscaping and evergreen screening shrub in our area. The pictures provided made it clear that scale was indeed the key problem. Many of the branches were covered in a white crusty substance which looks like a fungus but is actually numerous small scale insects covered in a white waxy protective body covering. The tiny insects are sucking on plant sap.

To manage scale on laurels, it is best to start pruning out branches that are dead or dying. Small infestations can be removed physically using a soft brush and soap and water. For larger infestations, treatment depends on time of year and the stage of the insect. In spring when temperatures are expected to stay above 40 degrees, a horticultural oil spray can be applied just before eggs hatch. Later in the year, a soil drench containing Imidacloprid can be applied, which is taken up by the roots of the plant and distributed to the branches and leaves. Systemic pesticides take time to work to absorb the chemicals through the body of the plant to then affect the insects. If there is no improvement, a repeat application of the drench can be made anytime as long as the ground is not frozen.

• Laurels May Be Hardy, But Beware of Problems, Fairfax Gardening
• Cherry Laurel: Identify and Manage Problems, University of Maryland Extension
• Scale Insects, Virginia Cooperative Extension

Eggplant Stress

There are brown leaves showing on my eggplant. I noticed some brown leaves at the top of the plant, trimmed them off, and tried to shade the plant slightly behind another plant. The following day, however, more leaves showed brown edges. The plant is in full sun for at least 8 hours. Is the plant getting too much sun or is there was some other issue?
– Jean / August 2025

Eggplants are warm season vegetables but grow best when temperatures are 70-85°F, and typically do well in 8 to 10 hours of sun. In July, most of our area had 18 days with temperatures above 90°F and high humidity, so even warm-temperature-loving vegetables could start showing stress such as this. Since the leaves are browning more at the top of the plant, sun scald is a possibility. Other possibilities include nutrient deficiency, watering or soil drainage problems, or even a disease issue. Beyond ensuring good watering practice (consistent moisture, watering early in the day and towards the base of the plant) and fertilizing, we advise you to submit a sample for free evaluation by our Diagnostic Lab to evaluate for disease.

• Growing Eggplant in the Vegetable Garden, Fairfax Gardening
• Eggplant, Virginia Cooperative Extension
• Eggplant Insect Pests and Diseases, Clemson Cooperative Extension

Hammerhead Worms

I found one or two hammerhead worms in my garden, I understand these are invasive. What should I do?
– Jane / July 2025

Hammerhead worms are an invasive species in the United States. Native to Asia, they have been in the US since the early 1900s. They can grow to nearly 2 feet (60 cm) and feed on earthworms, insects and mollusks. They prefer living in a moist organic matter. There are several things to remember when encountering one of these creatures.

Because they have a toxic mucus which they use to stun their prey, it is best not to touch the worms without gloves. The mucus can be toxic to pets if eaten. It can cause irritation to skin in humans.

Put the worms into a container or bag where it cannot escape, adding salt, soapy water or hand sanitizer. Seal the container/bag and dispose of it in the trash after the worms have died. Do not cut the worms or split the worms as they can fully regenerate. You do not need to report sightings to Virginia Cooperative Extension.

• Toxic hammerhead worms; expert provides advice for dealing with the invasive species at home, Virginia Tech News
• Hammer time in the DMV: Hammerhead Worms, Bug of the Week, University of Maryland

Blight on Sweet Woodruff

Sweet woodruff in my garden had flourished for a couple of seasons but this year, it was suddenly starting to die off. Some leaves look healthy, while others are deteriorating. What is causing this and what could I do to save it.
– Sonja / June 2025

Sweet woodruff, Galium odoratum, is a perennial groundcover that blooms in spring with tiny white flowers. It spreads via a creeping rhizome and has bright green leaves which whorl around the center stems. It does well in part to full shade, preferring moist soils but tolerant of dry shade as well.

This plant has likely become infected with a fungal disease such as Rhizoctonia root/stem rot, Rhizoctonia web blight or Southern blight. Given that the leaves appears to be dying back before the stems, it is likely a blight. Rhizoctonia is often found attacking smaller plants like sweet woodruff and results in foliage rapidly turning brown and black with quick dieback. Hot, humid weather, combined with the rain Fairfax County has received, can cause fungal diseases to flourish. Remove and destroy infected plant material to slow the spread of disease. Cultural practices such as avoiding overhead irrigation, irrigating early in the day and thinning plants are best for managing and avoiding future fungal outbreaks. For a definitive fungus identification and fungicide recommendations, submit a sample to our Diagnostic Lab.

• Rhizoctonia Web Blight on Flowers, University of Maryland Extension
• An Overview of Southern Blight, Virginia Cooperative Extension

Black and White Striped Beetle

A black and white beetle-like insect with a red head looks to be damaging my lavender, oregano, and obedient plant. The damage looked like a group of small brown dots on the leaves, and I am guessing it had started about one to two weeks ago.
– Elizabeth / May 2025

The four-lined plant bug (Poecilocapsus lineatus) has yellowish-green bodies with 4 black stripes and an orange head. They are native to North America and produce one generation a year, with the adults being most active during May. The bugs feed by piercing leaves with their needle-like mouthparts, removing chlorophyll while they feed, and injecting an enzyme that results in brown spots on the leaves. They are particularly attracted to herbs, like our client’s lavender and oregano, which helped confirm the identification.

Damage is brief and plants can typically recover by mid-summer. Pruning out the damage in June after the adults are done feeding, is an option to rejuvenate the plants. The adult bugs have wings and move quickly, so control with a contact insecticide is difficult. They lay eggs in vertical slits along the stems of plants, and the eggs overwinter inside the slits. The best control is to cut back plants at the end of the season and remove the plant material to prevent a new spring generation.

• Four Lines, One Bug, Fairfax Gardening
• Plant Bugs on Flowers, University of Maryland-Extension