Plant care guide
Umbrella Plant Scale Treatment: Scrape, Prune, Oil
Updated
Why does my Schefflera have scale?
Small, immobile tan or brown bumps on schefflera stems and leaflet undersides, often with sticky leaves and black sooty mould, are scale insects. Clemson lists schefflera among the houseplants that should not be sprayed with insecticidal soap, so treatment relies on scraping, pruning and a labeled oil or systemic product.
What to do first
Isolate the plant and scrape off every scale you can reach, checking each leaflet underside and the stems. Prune heavily infested shoots. For follow-up, test a horticultural oil labeled for houseplants on a few leaflets first, and skip insecticidal soap on schefflera.
Sticky leaflets and a black film on a schefflera usually lead back to scale. It is a familiar problem on this plant: Clemson’s schefflera factsheet lists scale insects with mealybugs and mites as its common pests, and NC State says scale can be a serious problem on the dwarf umbrella tree. The treatment needs one adjustment for schefflera, covered below.
Confirm it is scale
Clemson HGIC’s houseplant pests factsheet describes scale adults as small, immobile and legless, 1.5–13 mm (1/16–1/2 in) across. They sit mostly on stems and leaf undersides.
On a schefflera, check:
- Each leaflet underside. Clemson describes leaves made of oval leaflets arranged like umbrella spokes, up to 12 on older umbrella trees. Turn every one.
- The leaf stalks and stems, especially where the leaflets join.
- Sticky, shiny leaflets and black mould. UF/IFAS lists scale and sooty mould as a minor problem of Schefflera actinophylla. Clemson explains that sooty mould grows on the honeydew soft scales excrete.
University of Maryland Extension lists Schefflera among the hosts of brown soft scale. It describes mature females as oval and tan to yellow-brown with darker mottling, up to about 5 mm (3/16 in) long. Clemson notes that armored scales leave no honeydew, so a clean leaf does not rule scale out.
Skip insecticidal soap on schefflera
This is the plant-specific catch. In its notes on insecticidal soap, Clemson HGIC 2252 names schefflera among the houseplants that are sensitive to soap and says it should not be applied to them. Clemson adds that pesticide injury shows as distorted, yellowed, spotted or burned leaves, often within 5 to 10 days.
Many general scale guides recommend soap for crawlers. On a schefflera, use the other options below instead.
What to do
- Isolate the plant. UMD advises quarantining plants with scale. Clemson notes that control can take several weeks.
- Scrape off the adults. Clemson says early infestations can be scraped off with a fingernail. UMD adds a toothpick, cotton swab or soft toothbrush. Work along stems and under every leaflet.
- Prune heavily infested shoots. Bag the trimmings. Wear gloves: NC State says the sap of umbrella tree can irritate skin.
- Use oil, tested first. Colorado State Extension rates spray oils as the most effective treatment for scale (CSU: Managing Houseplant Pests). Choose one labeled for houseplants. Clemson advises testing any insecticide on a small part of the plant before treating the whole plant.
- Consider a systemic, by label. UMD lists systemic products labeled for indoor plants, usually imidacloprid-based, but notes they work on brown soft scale only. Colorado State says systemics give poor control of armored scales.
- Keep going. Colorado State says coverage must last a whole generation, two to four months. It also notes that dead scales can stay attached and look alive, so judge progress by new growth and fresh stickiness.
UMD advises discarding heavily infested plants. Colorado State agrees they are often best discarded.
Pets and children
The ASPCA lists schefflera as toxic to dogs and cats because of calcium oxalate crystals. Signs include mouth irritation, drooling, vomiting and difficulty swallowing. Keep pets away from trimmings and treated foliage.
Prevent a return
- Quarantine new plants. Clemson suggests six weeks, checking leaf undersides weekly.
- Inspect before bringing a plant back indoors after summer outside, including the outside of the root ball, as Clemson advises.
- Wipe leaflets. Clemson suggests washing smooth-leaved plants every two to three weeks, or wiping both surfaces with a soft, wet cloth.
Scale is one of three common schefflera pests; our schefflera pests guide covers spider mites and mealybugs. For scale biology across houseplants, see scale insects on houseplants. More care pages are on the schefflera hub.
Related guides
Other schefflera problems we cover: identification, leaf drop.
References
- Clemson Cooperative Extension HGIC 2252: Common Houseplant Insects & Related Pests
- Clemson Cooperative Extension HGIC 1511: Schefflera
- UF/IFAS Extension ST585: Schefflera actinophylla
- University of Maryland Extension: Scale Insects on Indoor Plants
- Colorado State University Extension: Managing Houseplant Pests
- NC State Extension Gardener Plant Toolbox: Heptapleurum arboricola
- NC State Extension Gardener Plant Toolbox: Heptapleurum actinophyllum
- ASPCA Animal Poison Control: Schefflera
How this guide was put together: Clemson Cooperative Extension, UF/IFAS Extension, University of Maryland Extension, Colorado State University Extension, NC State Extension and ASPCA guidance.