Boxwood Blight: Signs and What to Do

Boxwood blight is a fast-moving fungal disease that strips boxwoods of their leaves, usually starting low in the plant during warm, humid weather. Its giveaway signs are dark leaf spots with darker rims, sudden leaf drop, and narrow black streaks on green stems. Other boxwood problems such as winter burn, root rot and leafminer cause browning too, but they do not produce those black stem streaks. If you confirm blight, the standard response is to bag and remove infected plants and fallen leaves, sanitize tools and shoes, and replace with tolerant boxwood cultivars or a different shrub. Fungicides can protect healthy plants nearby but do not cure infected ones. Here is how to identify it, what to do next, and what to plant instead.

Part of our Trees & Shrubs guide →

In this guide

1. What Boxwood Blight Is
2. Signs of Boxwood Blight
3. Boxwood Blight vs Other Browning
4. What to Do If You Have Boxwood Blight
5. Preventing Boxwood Blight
6. Blight-Tolerant Boxwoods
7. Replacement Plants for Boxwood Hedges
8. A Seasonal Watch List
9. Caring for Healthy Boxwood Afterward
10. Frequently Asked Questions

What Boxwood Blight Is

Boxwood blight is caused by the fungus Calonectria pseudonaviculata (and a closely related species in Europe). It was first confirmed in the US in 2011 and has since been found in many states across the East, Midwest and Pacific Northwest. It infects boxwood (Buxus), and also pachysandra and sweet box (Sarcococca), which are often planted alongside boxwood in shady beds.

The fungus produces sticky spores that spread by splashing water, on pruning tools, gloves, shoes and clothing, on animals, and most commonly on infected nursery plants and holiday boxwood greenery. It thrives in warm, humid weather, roughly 60 to 85°F with long periods of leaf wetness. It also forms resting structures in fallen leaves that can survive in soil and debris for years, which is why replanting in an infected bed is risky.

Signs of Boxwood Blight

• Leaf spots: light to dark brown circular spots, often with a darker brown border or concentric rings. Spots may merge until the whole leaf browns.
• Rapid leaf drop: infected leaves fall within days to a couple of weeks, often starting at the bottom of the plant and moving up. Bare lower stems with leaves still on top are typical.
• Black stem streaks: narrow, dark brown to black lesions on green stems, often diamond-shaped or in streaks. This is the most diagnostic sign.
• White fuzz: in humid conditions, fuzzy white spore masses may appear on the undersides of infected leaves.
• Patchy spread: in a hedge, several plants decline in a short span, often after a humid, rainy stretch.

Infected plants usually are not killed outright by the first round; they may try to leaf out again, but repeated defoliation weakens them, especially highly susceptible types like English boxwood.

Boxwood Blight vs Other Browning

Problem	What it looks like	Key difference from blight
Boxwood blight	Dark-bordered spots, fast leaf drop, black stem streaks	Black streaks on green stems; leaves fall quickly
Winter burn	Bronze, tan or orange foliage on exposed sides after winter	Appears in late winter or spring on sunny, windy sides; leaves often stay attached
Volutella blight	Leaves turn straw-colored on individual branches; salmon-pink spores on stems	Pinkish-orange spore masses; affects branches, often after pruning or injury
Phytophthora root rot	Whole plant dulls, yellows and wilts; brown roots	Root and lower stem decay; often in wet, poorly drained soil
Boxwood leafminer	Blistered, yellow or brown leaves with larvae inside	Puffy blisters on undersides; tiny orange larvae when peeled
Macrophoma leaf spot	Tiny black dots on old, yellow leaves	Cosmetic, on old leaves only; no leaf drop wave

If you are unsure, our guides on why boxwood turns brown and why boxwood dies cover the non-blight causes in detail. For a definitive answer, bag a sample in a sealed plastic bag and take it to your county extension office or send it to your state’s plant disease clinic. Some states track and regulate boxwood blight, so a confirmed case may also be useful to them.

What to Do If You Have Boxwood Blight

1. Stop the spread

• Avoid working in infected plants when they are wet.
• Do not shear or prune healthy boxwood after touching infected plants without cleaning tools and changing gloves.
• Clean pruners and shears with a disinfectant such as 70 percent alcohol or a household disinfectant spray, and clean shoes and kneepads before moving to other beds.
• Wash clothing that brushed against infected plants.
• Do not share tools with neighbors without cleaning them.

2. Remove infected plants and debris

For lightly infected plants in an otherwise healthy hedge, some homeowners cut out infected branches and protect the rest with fungicide, but in most home landscapes the most reliable approach is to remove heavily infected plants entirely. Dig them out carefully, place the whole plant, roots and soil ball in heavy contractor bags, and dispose of them in household trash or as your local extension service advises, never in the compost or yard waste. Rake up and bag all fallen leaves, and remove the top inch or two of mulch under the plants as well, since that is where infected leaves collect.

3. Protect remaining plants

Fungicides do not cure infected boxwood, but protectant fungicides labeled for boxwood blight, such as products containing chlorothalonil, can help shield healthy plants nearby during humid periods. Apply as the label directs, typically every 7 to 14 days during warm, wet weather, and get good coverage inside the plant. For large or historic hedges, a certified arborist or licensed applicator can set up a program. Fungicides are a holding strategy, not a long-term fix for susceptible varieties.

4. Improve growing conditions

• Water at the base with soaker hoses or drip, not overhead sprinklers.
• Thin dense plants slightly to improve airflow; avoid heavy shearing that creates a tight, humid outer shell.
• Space new plants so leaves dry quickly after rain.
• Keep a 2 to 3 inch layer of fresh mulch under boxwoods to reduce soil splash onto lower leaves.

Preventing Boxwood Blight

• Buy boxwood only from nurseries that participate in a boxwood blight cleanliness program or can tell you where plants were grown.
• Quarantine new boxwood in a separate area for a few weeks and watch for symptoms before planting.
• Do not use boxwood greenery in holiday wreaths near your landscape plants, and bag it for the trash afterward.
• Hire landscapers who sanitize tools between properties.
• Choose tolerant varieties for new plantings.

Blight-Tolerant Boxwoods

No boxwood is immune, but breeding and trial work have identified varieties that hold up much better. NewGen Freedom and NewGen Independence were developed specifically for boxwood blight tolerance and are increasingly available. Trials have generally found English boxwood (Buxus sempervirens ‘Suffruticosa’) and American boxwood among the most susceptible, while many littleleaf and Korean boxwood selections are more tolerant. Results differ between trials and climates, so check your state extension recommendations and nursery labeling. Our guide to boxwood varieties compares sizes and habits.

Replacement Plants for Boxwood Hedges

If blight keeps returning, or you want to avoid it entirely, several evergreen shrubs give a similar clipped look. Do not plant pachysandra or sweet box as companions, since they are also hosts.

Plant	USDA zones (typical)	Typical size	Notes
Inkberry holly (Ilex glabra), compact types like Gem Box or Shamrock	4 to 9	2 to 4 ft	Native; tolerates wet soil; small glossy leaves
Japanese holly (Ilex crenata)	5 to 8	2 to 6 ft	Very boxwood-like; dislikes poorly drained soil and can get mites
Dwarf yaupon holly (Ilex vomitoria ‘Nana’)	7 to 10	3 to 5 ft	Heat and drought tolerant; excellent in the South
Japanese yew (Taxus), compact types	4 to 7	2 to 6 ft	Takes shearing and shade; deer browse it; toxic to people and pets
Dwarf English laurel or cherry laurel cultivars	6 to 9	3 to 6 ft	Larger leaves; fast growing; good screen

For a side-by-side look at the closest substitute, see our comparison of Japanese holly vs boxwood. When you replant a bed where blight occurred, remove old mulch and leaf debris, add fresh soil and mulch, and choose a non-host plant or a tolerant boxwood.

A Seasonal Watch List

Season	What to do
Late winter	Prune in dry weather; clean tools; refresh mulch; note any winter burn so you do not confuse it with blight later
Spring	Inspect new purchases and quarantine them; start checking lower branches after rainy spells
Summer	Peak risk during warm, humid stretches; inspect every couple of weeks; water at the base only
Fall	Second risk period with cool, wet weather; rake and bag fallen leaves under boxwood
Holidays	Keep boxwood wreaths and garland away from garden plants and bag them for the trash

If you have a long or valuable hedge, a historic planting, or blight that has appeared in several beds, it is worth bringing in a certified arborist or a landscape company that follows boxwood blight sanitation practices. Ask how they clean tools and equipment between properties before they set foot in your yard, since contaminated crews are a common way the disease moves from one property to the next.

Caring for Healthy Boxwood Afterward

Prune remaining boxwoods in dry weather, ideally late winter or early spring, and thin rather than shear when you can. Our guide to pruning boxwood covers technique. Inspect plants every few weeks during humid summer stretches, starting with lower interior branches where blight often begins. For more on keeping hedges and landscape shrubs healthy, see the trees and shrubs guide.