Save Your Boxwoods
- Oflahertys Landscaping
- Mar 2
- 2 min read
Boxwoods (Buxus spp.) have long been a staple of Ontario gardens, prized for their dense, evergreen foliage and ability to shape formal hedges, borders, and topiaries. Yet in recent years these classic shrubs have come under increasing pressure from a combination of invasive pests and diseases that can quickly turn a thriving hedge into a dying one.
What's Threatening Boxwoods Today?
Box Tree Moth: Larvae chew large holes in leaves, defoliating the plant.
Boxwood Leaf Miner: Small maggots tunnel between leaf layers, causing “mined” blotches.
Boxwood Blight: Fungal disease that kills shoots and causes die‑back.
Boxwood Psyllid & Other Insects: Sap‑sucking insects cause cosmetic damage and stress.
These problems are amplified during hot, dry summers—conditions Ontario has experienced more frequently in recent years. Because each issue alone may not kill a shrub, their combined impact can be devastating if left unchecked.
What can you do?
Keep problems out before they arrive by choosing resistant varieties such as 'Winter Gem' or 'Green Gem' that have shown tolerance to blight and pests in the region. Plant in a location with partial shade and good air circulation. Mulch with a layer of organic material to retain moisture but keep away from the trunk to avoid rot and monitor regularily! Inspect your shrubs weekly during the growing season as early detection will make treatment easier.
How to rescue an infested Boxwood
Prune out infected branches as soon as you spot blight lesions or severe defoliation. –
Cut at least 30 cm below the visible symptoms and dispose of the material in sealed bags—do not compost.
Insecticide for Box Tree Moth & Leaf Miner. – Apply a registered pyrethroid or neem‑based spray early in the season (first signs of egg laying). Follow label directions and re‑apply after rain.
Fungicide for Boxwood Blight – A systemic fungicide containing chlorothalonil or boscalid can protect healthy tissue and limit spread. Apply at the first sign of lesions and repeat according to the product schedule.
Beneficial Nematodes – Introduce nematodes that target leaf‑miner larvae in the soil.