Boxwood

Seasonal Pest & Disease Calendar

Pest & Disease Guide (Homeowner-Friendly)

1. Boxwood Leafminer

Symptoms

• Blistered, puffy, or “bubbled” leaves
• Leaves may turn yellow, orange, or brown
• Squishy feel when pressed
• Adult orange gnat-like flies in spring

Treatment

• Prune out damaged leaves in spring
• Systemic insecticides (imidacloprid, dinotefuran) in mid-summer
• Avoid shearing during adult flight (early spring)

2. Boxwood Psyllid

Symptoms

• New leaves cup inward (“taco shell” shape)
• White, waxy psyllid nymphs inside cupped leaves
• Light stunting of new growth

Treatment

• Usually cosmetic
• Prune off cupped tips in early summer
• Systemic insecticides if severe (spring)

3. Spider Mites (Boxwood & Two-Spotted)

Symptoms

• Tiny yellow stippling on foliage
• Leaves turn dull, dry, or bronze

• Webbing minimal but present
• Tap-test over white paper reveals tiny moving specks

Treatment

• Strong water spray to knock mites off
• Miticides if severe (summer)
• Avoid hot, dry stress—water deeply

4. Volutella Blight

Symptoms

• Leaves turn tan or straw-colored
• Blackened stems
• Pinkish fungal spores under humid conditions
• Patchy dieback

Treatment

• Prune infected stems to healthy green wood
• Sanitize tools
• Improve airflow & avoid overhead irrigation
• Mulch and deep-water to reduce stress

5. Boxwood Dieback (Fungal Complex)

Symptoms

• Random branches die back
• Leaves fall prematurely

• No clear pest cause
• Often triggered by stress (winter burn, drought, poor drainage)

Treatment

• Correct watering
• Avoid shearing too aggressively
• Prune out dead stems

• Improve soil drainage
• No single chemical cure—focus on health

6. Winter Burn / Desiccation

Symptoms

• Orange or bronze discoloration, especially on south/west exposures
• Leaf tips dry out and flake
• Entire sections may brown in severe winters

Treatment

• Winter watering every 4–6 weeks (as needed)
• Burlap wind protection in exposed areas
• Mulch 2–3" around the base
• Spring pruning to remove dead tips

When to Worry vs. When It’s Cosmetic

When to Worry (Action Needed)

• Whole branches die back (possible blight or root issues)
• Severe leaf blistering every year (leafminer infestation)

• Large areas bronzing or turning orange after winter
• Shrub shows thinning growth and poor vigor
• Presence of pink spores (Volutella)

Mostly Cosmetic (Monitor Only)

• Light winter bronzing that fades in spring
• Minor leaf cupping from psyllid
• Occasional mite stippling during hot, dry periods
• Small blister patches without recurring issues