Boxwood Blight or Volutella Blight? 4 Signs to Check Before You Pull Out the Hedge
Boxwood diseases: black stem streaks and fast leaf drop point to boxwood blight; tan leaves that stay on point to Volutella. Four signs, and when to pull.
In short
- Boxwood diseases: black streaks on green stems and fast leaf drop point to blight; tan leaves that stay on and pink-salmon spores point to Volutella.
- A lab test confirms boxwood blight, and fungicide can mask its symptoms.
- Confirmed blight: remove and bag the plants (Virginia Tech’s default). Volutella: prune out dead branches.
- Checked against: University of Kentucky, Virginia Tech, UC IPM, Penn State, Illinois Extension.
A hedge that turns brown in spring or summer may have either of two boxwood diseases, and they call for opposite responses. Boxwood blight (Calonectria pseudonaviculata) is the one that, in Virginia Tech’s best-practice guide for home landscapes, “cannot be effectively controlled once the infection begins,” so the advice is to remove diseased plants promptly. Volutella blight (Pseudonectria buxi) is a wound-and-stress fungus that extension services handle with pruning and sanitation.
Four signs help you tell them apart. None replaces a lab test, so this guide also covers what to send in, what not to do first, and what each verdict means for your hedge.
How do you tell boxwood blight from Volutella blight?
Look at four things on an affected stem: black streaks, whether dead leaves drop or stay, the colour of any spore growth, and when the damage started. Boxwood blight leaves black streaks and drops its leaves fast. Volutella blight leaves no streaks and its dead leaves hang on. That contrast comes from the University of Kentucky’s Volutella fact sheet, and the table adds the rest.
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| What to check | Boxwood blight | Volutella blight |
|---|---|---|
| Green stems | Elongated dark brown or black streak-like lesions | Sunken, discolored cankers with loose bark; no black streaks |
| Dead leaves | Drop rapidly, with the lower canopy often going first | Cup upward and stay attached for a long time, though they may eventually drop |
| Spore growth in humid weather | White fungal growth on leaves and twig lesions | Pink to salmon masses on leaf undersides and cankered stems |
| Timing | Warm summer weather with rain or high humidity | Late winter to spring, on last year’s growth, before new growth starts |
| What starts it | Spores arriving by water splash or on tools, clothing, wet hands and infected plants | Stress and wounds: winter injury, pruning cuts, drought, sunburn |
| Cultivar picture | Varies by cultivar; none is immune | All species and cultivars are susceptible |
Weather won’t settle it: Kentucky puts blight’s optimum at 64–81°F and Volutella’s at 68–77°F with humidity above 85%, so one warm, wet week suits both. The calendar helps more. UC IPM says boxwood blight symptoms develop later in the growing season, during summer, while Volutella shows in late winter or spring on shoots infected the year before. Spore colour is a useful field check: Penn State’s boxwood disease table gives white growth for blight and pink to salmon for Volutella.
Three things keep this from being a clean test:
- One plant can have both. UC IPM says the same plant can be affected by boxwood blight and Volutella blight. Kentucky says look-alike problems may occur together and that Volutella often develops on winter-injured tissue. Finding Volutella does not rule blight out.
- Black streaks are not exclusive. Illinois Extension describes Fusarium canker as dark brown or black streaks along branches that look very similar to blight’s, and says the spores must be seen under a microscope to separate the two.
- Tolerant cultivars hide it. Kentucky says symptoms on tolerant cultivars are often subtle and go unnoticed.
Illinois’s plant clinic says boxwood blight “can be a challenging disease to identify outside a plant diagnostic laboratory.”
Boxwood blight: why some hedges go bare in a week
Boxwood blight moves fast because its spore cycle is short. Kentucky’s fact sheet says spores can start an infection within 5 hours of landing on a susceptible plant, and new spore-producing lesions can form within 7 days. The best weather for it is 64–81°F; symptoms are suppressed above 84°F.
Within a week American boxwood cultivars can lose their leaves to boxwood blight, and weakened plants can die within one growing season.
Source: Gauthier and Dockery, Boxwood Blight (PPFS-OR-W-20), University of Kentucky
The first symptoms are light or dark brown circular leaf spots with darker borders. Many owners never see them, because plants can drop their leaves soon after the spots form; Kentucky’s photo captions note that loss of the lower canopy is often the first obvious symptom. The stems then show elongated dark brown or black lesions. Virginia Tech’s guide lists the same three signs.
The spores are sticky. Rain splash and wind-driven rain carry them short distances, and they rarely move unaided by people. They hitchhike on tools, clothing, holiday decorations and wet hands, and they travel far only on infected plants, infested soil or equipment. Virginia Tech’s guide reports blight spreading between two North Carolina landscapes on a spray hose used for leafminer control, and it says the fungus is not well adapted to long-distance spread on air currents. Its practical rule is to stay out of the hedge when the foliage is wet.
Pachysandra and sweetbox (Sarcococca) belong to the same plant family as boxwood and are susceptible too, so check any pachysandra under the hedge for brown leaf spots. Our guide to hedge problems sets blight beside bare patches and overgrowth if you are not sure the damage is a disease at all.
Volutella blight: the fungus that needs a wound
Volutella blight is a weak-tissue disease. Kentucky’s extension plant pathologists call it the most common boxwood disease in Kentucky landscapes and nurseries, and say the fungus attacks leaves and stems of damaged or stressed plants. Winter injury, poor vigor and stem wounds raise the risk.
68–77°F with humidity above 85% are the optimal conditions for Volutella blight infection and disease development.
Source: Leonberger and Gauthier, Volutella Blight of Boxwood (PPFS-OR-W-26), University of Kentucky
The spores get in at the base of small dead shoots, in branch crotches where fallen leaves collect, through pruning wounds and in winter-damaged areas. They are wet and sticky, so they travel only short distances on air; people move them on infected plants, cuttings, hands, gloves and tools.
Shoots infected the previous season fail to grow in spring. Their leaves turn light green-yellow, then red or bronze, then straw-tan, and they cup upward. The fungus forms stem cankers, sunken lesions that girdle the stem, and UC IPM says it kills shoots and leaves from the canker outward. So if you trace a dead shoot back to where green leaves begin, you find sunken, discolored bark at that line, loose around older cankers. In humid weather pink to salmon spore masses (sporodochia) appear on the leaf undersides and stems, visible with or without a hand lens.
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→ View My Garden CalendarWinter injury is a look-alike that trips people up. Kentucky says it kills foliage on the parts exposed to harsh, drying winter winds while protected branches are unaffected, and Illinois adds the “snow line,” a clean line between a healthy green bottom and a damaged top. Illinois adds that Volutella “progresses down the stem, whereas winter injury happens seemingly at once.” The two often occur together, so pink-salmon spore masses on damaged tissue help confirm Volutella.
What else turns boxwood brown?
Several other problems get mistaken for these two. Illinois Extension lists winter injury, Macrophoma leaf spot, Phytophthora root rot, Fusarium canker and boxwood leafminer among blight’s look-alikes, and Penn State’s table of boxwood problems adds nematode damage.
| What you see | Likely cause | Clue that sets it apart | What to do next |
|---|---|---|---|
| Tan to bronze foliage on one side or the top | Winter injury | Worst on southwest and windward sides; a snow line splits healthy bottom from damaged top (Illinois) | Protect plants from drought and drying winds in autumn and winter (Penn State) |
| Straw-yellow leaves dotted with small black bumps | Macrophoma leaf spot | Black, raised fruiting bodies on dead or dying leaves; infects only leaves already weakened by winter (Illinois, Penn State) | Find the stress behind it; protect from wind, salt spray and salt runoff (Penn State) |
| One branch wilts; pale green leaves turn brown and shriveled | Phytophthora root rot | Heavy, wet soil; roots dark brown or black and sparse; discolored tissue under the bark at the stem base (Illinois) | Test root or base tissue; improve drainage, avoid overwatering, do not replant susceptible plants there (Illinois) |
| Dark brown or black streaks on branches | Fusarium canker | More often at branch tips, where blight may be near the base or middle; Illinois’s clinic has seen it only on nursery or greenhouse samples | Needs a microscope to separate from blight, so send a sample |
| Off-green pouches that turn brown; light-brown mottling in spring | Boxwood leafminer | Mottling shows on both leaf surfaces while other foliage is green (Illinois) | An insect, not a fungus: ask your extension office about control timing |
| Stunted growth, bronzed leaves, general decline | Root nematodes (Pratylenchus) | Small roots have brown dead areas that spread to engulf the root tips (Penn State) | No adequate controls once infected; do not replant a susceptible plant unless the site is fumigated first (Penn State) |
Roots and stems give away what leaves cannot: dark roots point to Phytophthora or nematodes, black stem streaks to blight or Fusarium, and sunken cankers with pink-salmon spores to Volutella.
How do you get boxwood blight confirmed?
Send a sample to your state’s plant diagnostic lab through your county extension office, and do it before you spray. Virginia Tech’s guide says confirmation matters because other boxwood problems get mistaken for blight, and because extension needs to know where outbreaks occur. In Illinois, boxwood blight is a regulated plant disease, so check your own state’s rules.
- Do not take it to a garden center. Illinois Extension says never to take a suspected sample to a garden center, nursery or other place that grows or distributes boxwood.
- Call extension first for your state’s submission form and rules.
- Cut stems that show the symptoms (black streaks, leaf spots or defoliation) and double-bag them in sealed plastic bags before you carry them anywhere, as Virginia Tech’s guide advises.
- Do not spray first. Fungicide treatment can suppress symptom development, and Virginia Tech warns that it can mask the disease on susceptible cultivars.
Should you rip out the hedge? What to do for each diagnosis
If it is Volutella blight: prune, sanitize and cut the stress
In the sources we read, Volutella blight is handled by pruning and sanitation rather than removal. The steps below combine Kentucky’s and UC IPM’s advice.
- Prune diseased branches when the foliage is dry, to avoid spreading the sticky spore masses, and never take more than one-third of the healthy branches in a year (UC IPM).
- Sanitize tools between plants with 70% isopropyl alcohol, a 10% bleach solution or a commercial disinfectant.
- Rake up fallen leaves and dispose of them away from the boxwoods. UC IPM adds that shaking the plants now and then knocks down dead leaves lodged in branch crotches.
- Water the soil, not the leaves, and give the plant enough water in dry spells. Avoid soggy soil and excess fertilizer.
- Thin dense inner growth, space plants so air moves through, and shield them from drying winter winds.
Sources split on sprays. Kentucky says fungicides are typically used only on nursery plants and commercial propagation stock, and do not cure branch infections. UC IPM suggests preventive sprays of Bordeaux mixture, another copper fungicide or chlorothalonil in late winter or early spring where the disease has been a problem, and Penn State says to protect new growth in spring and fall. All three agree on pruning in dry weather, thinning and clearing fallen leaves.
If boxwood blight is confirmed: three options
Confirmed boxwood blight leaves you three realistic choices, and only the first has you remove every susceptible plant. Virginia Tech’s guide describes two scenarios, and Kentucky adds a third for valued specimens.
| Option | What it takes | Fits when (our reading) |
|---|---|---|
| Remove all susceptible boxwood and replant with resistant cultivars | Virginia Tech’s second scenario: remove the plants including roots, clean up debris, replant with “most resistant” cultivars from a Boxwood Blight Cleanliness Program nursery. No repeated spraying. | The hedge is ordinary and you do not want a spray calendar |
| Remove the diseased plants and protect the rest | Virginia Tech’s first scenario for highly valued boxwood: remove diseased plants and leaf litter promptly, then repeat fungicide on susceptible survivors every 7 to 14 days through the growing season for the life of the plants. | The plants are valuable and most are still clean |
| Try to rehabilitate a valued plant | Kentucky says reports suggest aggressive pruning, rigid sanitation and fungicide, especially in wet seasons, may rejuvenate valuable specimens within 3 to 5 years, on a consistent spray schedule. | A single specimen worth years of effort |
So “rip out the whole hedge” is the right call mainly when blight is confirmed and you will not run a spray programme. Fungicide protects healthy tissue and does not cure: Virginia Tech says sprays begun after the disease is present do not give acceptable control, and Kentucky’s homeowner schedule is chlorothalonil every 10 to 21 days while conditions favor the disease, against Virginia’s 7 to 14.
If you remove plants, disposal matters as much as digging:
- Rake, sweep or vacuum leaf litter off the soil. If leaf debris has been worked into the soil, removing soil to a depth of 8 to 12 inches may help (Virginia Tech).
- Bag everything for the landfill, or bury it 2 feet deep away from boxwood. Never compost it.
- Sanitize tools, tarps, shoes and gloves. Virginia Tech’s guide gives 1 part household bleach to 9 parts water, mixed fresh, with at least 5 minutes of contact for tools. Bleach is corrosive, so oil the tools afterwards.
How long does boxwood blight stay in the soil? The figures differ
Virginia Tech’s guide says the fungus can persist in soil for 5 to 6 years, but a 2022 study found its soil population fell sharply within a year of removing blighted plants. The numbers are not all measuring the same thing.
| Source | What it says | What it covers |
|---|---|---|
| Virginia Tech, 2014 | Survival structures can persist in the soil for 5 to 6 years | Extension guidance for home landscapes |
| University of Kentucky, 2018 | Microsclerotia can stay dormant for 1 year buried in soil and for up to 6 years in plant debris; do not replant boxwood for at least 3 to 6 years | Extension guidance |
| Hong and colleagues, 2022 | The soil population fell sharply within the first year after blighted boxwood was removed and was almost undetectable by the end of the study | Soil baiting and sentinel plants in gardens in Virginia, California, Illinois, New York and South Carolina |
Both extension sheets predate the 2022 study, and Kentucky’s own wording separates plant debris (up to 6 years) from buried soil (1 year); its advice not to replant boxwood for 3 to 6 years is not tied to either figure. The study’s authors, publishing in Plant Disease, note that in the milder UK the fungus stayed recoverable in leaf debris for 5 years, conclude it did not survive in US garden soil as well, and write that the result challenges the notion that fungi making microsclerotia will always survive in soil for many years.
Our reading: treat leaf debris as the hazard and clean it up, and do not write the site off forever. This is one study in five states. It does not make replanting a susceptible cultivar safe.
Which boxwood should you replant, and how much room does it need?
Pick by cultivar name, and give the plants room. Virginia Cooperative Extension’s Boxwood Blight Task Force lists cultivars that research trials found resistant or tolerant, and others that were very susceptible. It calls its list a selection, and says new resistant cultivars will keep coming.
| Trial result | Cultivars on the task force list |
|---|---|
| Resistant or tolerant | ‘Green Beauty’, ‘Northern Emerald’, ‘Wedding Ring’, ‘Wintergreen’, ‘Golden Dream’, ‘Winter Gem’ (Buxus microphylla); ‘Nana’, ‘Franklin’s Gem’, ‘Wee Willie’ (B. sinica var. insularis); ‘Richard’ (B. harlandii) |
| Very susceptible | ‘Suffruticosa’, ‘American’, ‘Halifax American’, ‘Black American’, ‘Fineline’, ‘Justin Brouwers’ (B. sempervirens); ‘Morris Midget’ (B. microphylla var. japonica) |
Three cautions apply before you shop from that list:
- Tolerant is not immune. Virginia Tech says no boxwood is immune, and warns that partially resistant cultivars can act as a “Trojan horse” because they may carry the fungus without obvious symptoms. Kentucky agrees there is no true resistance.
- The species name is not a safe label. Penn State’s table lists Korean boxwood (B. sinica var. insularis) as susceptible, while the task force list has ‘Nana’, ‘Franklin’s Gem’ and ‘Wee Willie’ from the same variety as tolerant. Buy the cultivar, not the common name.
- Blight resistance does nothing for Volutella. Kentucky and UC IPM both say all boxwood species and cultivars are susceptible to it, so cultural care is the main defense there and sprays are preventive only.
The same layout rules cut the risk from both diseases, because both need wet leaves and still air. Virginia Tech advises mulching to reduce splash, avoiding overhead irrigation, choosing open-growing cultivars over dense ones like ‘Suffruticosa’, and giving adequate spacing; it goes as far as saying growers may want to avoid close spacing of boxwood and, therefore, hedges. Kentucky says to space plants widely. None of the sources we read gives a distance, so check the mature width on the plant tag and err on the wide side.
If boxwood stops looking worth the work where you live, our boxwood vs. privet comparison weighs it against a faster hedge, the list of hedge plants that need only one trim a year covers evergreen alternatives, and the full hedge plants growing guide sorts choices by zone and job.
Boxwood blight and Volutella blight: common questions
Can boxwood recover from boxwood blight?
Fungicides protect healthy tissue but do not cure the disease, and Virginia Tech says it cannot be effectively controlled once infection begins. Kentucky notes reports that aggressive pruning, strict sanitation and fungicide may rejuvenate a valued specimen within 3 to 5 years.
Does Volutella blight kill boxwood?
It kills the shoots and leaves beyond each stem canker, according to UC IPM; the sources we read describe shoot and branch dieback and give no plant-death rate. The standard advice is to prune those branches out on a dry day and to fix the stress behind it, since vigorous plants resist major problems better than stressed ones.
Can I compost clippings from blighted boxwood?
No. Virginia Tech and Kentucky both say not to compost diseased material. Bag it for the landfill, or bury it 2 feet deep away from boxwood.
What to do this weekend
Pick the three worst branches and look at the green stems under the dead leaves. Black streaks mean stop and get it checked: bag a sample, call your extension office, and do not spray or compost anything. No streaks, tan leaves that cup upward and salmon spore masses point to Volutella (it can occur together with blight, so confirm if unsure), so prune on a dry day, wipe the blades, and clear the fallen leaves. Either way, bleach the tools before you touch the next plant.
Sources
- Gauthier, N., and Dockery, J. Boxwood Blight (PPFS-OR-W-20). University of Kentucky Cooperative Extension, August 2018
- Leonberger, A., and Gauthier, N. W. Volutella Blight of Boxwood (PPFS-OR-W-26). University of Kentucky Cooperative Extension, August 2017
- Bush, E., Hansen, M. A., Dart, N., Hong, C., Bordas, A., and Likins, T. M. Best Management Practices for Boxwood Blight in the Virginia Home Landscape (PPWS-29NP). Virginia Cooperative Extension, May 2014
- Virginia Cooperative Extension Boxwood Blight Task Force. Boxwood blight-resistant and very susceptible cultivars. Virginia Tech
- Hong, C., Daughtrey, M., Howle, M., Schirmer, S., Kosta, K., Kong, P., Likins, M., and Suslow, K. Rapid decline of Calonectria pseudonaviculata soil population in selected gardens across the United States. Plant Disease 106(11):2831-2838, 2022, doi 10.1094/pdis-02-22-0443-re
- UC Statewide IPM Program. Volutella blight or Pseudonectria canker. University of California Agriculture and Natural Resources
- Cleveland, T., and Plewa, D. Boxwood Blight look-alikes. Good Growing, University of Illinois Extension, May 17, 2021
- Moorman, G. W. Boxwood Diseases. Penn State Extension, updated November 21, 2023
