How to Treat Scales on Tricolor Euonymus

Soak the soil with insecticide as a last resort.

The Euonymus species includes two groups of plants. There are those that grow as shrubs, such as the American euonymus, a deciduous plant that reaches a height of 6 feet. You also find a creeping ground cover, Euonymus fortunei, or wintercreeper euonymus, which sprawls 70 feet. One of the wintercreeper cultivars is the Euonymus fortunei 'Tricolor,' which has variegated leaves. That Euonymus variety, as well as all others, is susceptible to the Euonymus scale, an insect that feeds on plant sap. Unless controlled, an infestation may be fatal to the plant.

Things You'll Need

• Scouring pad
• Shears
• Horticultural oil
• Dormant oil
• Imidacloprid-based insecticide

Instructions

1. Scrape the scales off with your nails. The stationary adult insects will be arranged in a line along the central leaf vein. They also park themselves on stems. On thick plant tissue, use a scouring pad to remove the scales, scraping gently to prevent damage to the plant.

2. Prune branches that have scale infestations. Discard them in the trash.

3. Catch the scales while they're still crawlers in the spring. Just after the eggs hatch, the insects have a permeable soft body, unlike the chemical-resistant hard shell they develop as adults. Spray the babies with horticultural oil, following the manufacturer's instructions for the brand you select. Ask your cooperative extension office staff for a date estimate of when the scale eggs hatch in your area.

4. Spray the 'Tricolor' with dormant oil, a less refined horticultural oil for use when plants aren't actively growing, in late winter. Cover the undersides of all leaves and lateral and main stems with the product, following the manufacturer's instructions for application.

5. Drench the soil around the plant's base to the root zone using an insecticide that contains the chemical imidacloprid. The roots absorb the pesticide, which then circulates through the plant, poisoning the scales that feed on the sap. Follow the manufacturer's instructions for application rates for the brand you select.

References

• Clemson Cooperative Extension: Euonymus
• Learn2Grow: Euonymus Fortunei 'Tricolor'
• Clemson Cooperative Extension: Euonymus & Insect Pests
• Virginia Cooperative Extension: Euonymus Scale
• University of Kentucky College of Agriculture: Euonymus Scale