Viburnum Leaf Curl and Sticky Webbing: Mite or Scale Infestation

Decoding the Symptoms

Viburnum carlesii with chronically curled, shriveled leaves, brown spots on undersides, and sticky white cobwebby growth over three years indicates a persistent sap-feeding pest complex: spider mites, scale, or mealybugs. The webbing is characteristic of spider mites; sticky residue suggests scale/mealybug honeydew.

Systemic Treatment Protocol

Imidacloprid soil drench (Bayer Advanced) targets all three pests systemically. Apply at label rate for shrub size in early spring; repeat annually. Thorough coverage of root zone ensures uptake.

Confirming the Pest

• Spider mites: Tap foliage over white paper; look for moving specks.
• Scale: Oval bumps on stems/leaf veins; scrape with nail.
• Mealybugs: White cottony masses in leaf axils.

Cultural Support

• Water deeply during drought—stress increases susceptibility.
• Prune heavily infested branches.
• Avoid broad-spectrum sprays that kill predatory mites.

Systemic treatment breaks the multi-year cycle effectively.