How to Recognize and Manage Boxwood Blight in Your Home Garden

Boxwood shrubs are a classic, beautiful choice for home landscapes — but they’re under threat from a serious fungal disease called boxwood blight. First identified in Virginia in 2011, this disease spreads quickly and can cause defoliation and plant decline. If you have boxwood in your yard, here’s a simple guide to help you identify and manage boxwood blight so you can keep your garden healthy.

What Is Boxwood Blight?

Boxwood blight, also known as box blight, is a severe fungal disease caused by the fungus Calonectria pseudonaviculata. It leads to defoliation and decline in susceptible boxwood plants. First identified in a Carroll County nursery in Virginia in 2011, it spread to other commercial nurseries and landscapes across several counties by fall 2013.

Once established in a landscape, controlling boxwood blight with fungicides becomes challenging and expensive. The disease primarily spreads through contaminated plant material, such as container or field-grown boxwood and boxwood greenery used for holiday decorations. However, spores can also transfer via pruning tools, clothing, equipment, and anything that contacts infected plants.

Home gardeners can protect their boxwood by implementing preventive measures to avoid introducing the disease into their landscapes.

Symptoms to Watch For

Keep an eye on your boxwood plants and look for these telltale signs of blight:

Brown spots on leaves with dark edges
Leaf drop, starting from the lower branches and moving upward
Black streaks on stems
Thinning and defoliation, leaving bare branches

Other plants like Japanese spurge (Pachysandra terminalis) and sweetbox (Sarcococca) can also carry this disease, so check those as well.

How to Prevent Boxwood Blight

Buy your boxwood from nurseries that are part of the Boxwood Blight Cleanliness Program. This ensures you’re starting with healthy plants that are less likely to carry the disease.
Keep those leaves dry and let the air flow around your boxwood to keep disease at bay. Here’s how:
- Skip the overhead watering. Instead, water at the base of the plant to keep the foliage dry. Wet leaves are a breeding ground for blight.
- Space out your plants to boost air circulation. Tight hedges? Maybe not the best idea. Adequate spacing helps prevent the spread of disease by allowing air to move freely between plants.
- Mulch around your boxwood to stop water from splashing blight spores onto the leaves. A good layer of mulch can also help retain soil moisture and suppress weeds.
- Avoid working in your boxwood garden when the leaves are wet to prevent spreading the fungus. Wet conditions make it easier for the blight to spread from plant to plant.
- Keep things clean: Don’t move infected soil or plant bits to areas with boxwood. Contaminated soil can harbor the fungus and spread it to healthy plants.
- Sanitize your tools, clothes, and tarps between different boxwood areas and other Buxaceae family members. This helps prevent the accidental transfer of spores.
- Bag up all boxwood debris (yes, even holiday greenery) and toss it in the landfill or bury it 2 feet deep, far from your boxwood. Proper disposal prevents the fungus from lingering and spreading.
- Be cautious about letting folks collect greenery from your property. If they visit multiple boxwood plantings and don’t follow good sanitation practices, they could introduce blight to your garden.
If you hire landscape professionals to spray or maintain your boxwood, discuss your concerns about boxwood blight with them. Learn about their management practices to ensure they’re taking steps to avoid moving blight from one client’s landscape to another. This conversation can help you decide if their approach aligns with your standards for protecting your garden.

What to Do If You Suspect Blight

Boxwood blight doesn’t travel far on its own, so it usually sneaks into your garden through infected plants or contaminated tools and gear. If you’ve got boxwood in your yard, follow these tips to keep this pesky disease at bay and protect your landscape.

If you see signs of boxwood blight, act quickly:

Collect a sample: Take a cutting of a symptomatic branch and double-bag it in plastic.
Get a diagnosis: Bring the sample to your local extension office for testing.
Remove infected plants: If blight is confirmed, remove diseased boxwood and leaf debris. Bag and dispose of them in the landfill — never compost.
Sanitize everything: Clean your tools, shoes, gloves, and even clothing to avoid spreading the spores.

What to do if boxwood blight is diagnosed in the landscape

Once boxwood blight sets in, it’s tough to control, so it’s best to quickly remove any infected plants to stop it from spreading to healthy ones. Don’t forget to clear away any fallen leaves too. Keep in mind, though, that just removing the infected plants and debris won’t completely get rid of the blight, as the fungus can linger in the soil for 5 to 6 years. This means planting new, susceptible boxwood in the same spot isn’t a great idea.

Right now, home gardeners don’t have many fungicide options, but pros working in home landscapes can access more products. There’s hope that ongoing research will eventually bring better solutions for home gardeners, cutting down on the need for frequent fungicide use.

Choosing Resistant Boxwood

If you’re planting new boxwood or replacing diseased ones, choose resistant varieties. Some good options include:

Buxus microphylla ‘Green Beauty’
Buxus microphylla ‘Golden Dream’
Buxus harlandii

These cultivars are less likely to get blight and require fewer fungicide treatments.

Final Thoughts

Caring for boxwood takes a little extra attention when it comes to boxwood blight, but with good practices and quick action, you can prevent the disease from taking hold in your garden. Keep an eye out for symptoms, choose plants wisely, and keep your tools clean — your healthy, green boxwood will thank you!

Source: Best Management Practices for Boxwood Blight in the Virginia Home Landscape from Virginia Tech. PPWS-29-pdf.pdf