Dogwood Tree Diseases: Anthracnose and the Other Big Threats

Flowering dogwood (Cornus florida) is one of the most-planted small ornamental trees in the eastern United States and one of the most fragile. A disease called dogwood anthracnose, introduced from Asia in the late 1970s, killed millions of dogwoods across the Appalachian and Northeastern forests in the 1980s and 90s. Wild populations still haven’t recovered in many areas, and backyard dogwoods continue to die from it every year.

Anthracnose is the disease to learn first. The other four problems on this list (powdery mildew, septoria leaf spot, crown canker, and dogwood borer) are easier to manage but still threaten landscape dogwoods, especially in stressful site conditions. Crown canker is the second most likely to kill the tree.

If you’re planting new and want a dogwood that won’t get hammered by these problems, the answer is Cornus kousa (Kousa dogwood) or one of the C. florida × C. kousa hybrids. The article covers cultivar choice in detail.

How to tell which disease you’re looking at

Quick visual triage. Find the most obvious symptom and jump to the section below.

• Brown spots with purple-brown margins on leaves, twig dieback, lesions on the trunk: dogwood anthracnose
• White powdery coating on new leaves, often with reddish discoloration and leaf scorch: powdery mildew
• Small angular purple-bordered spots on leaves in late summer, premature leaf drop: septoria leaf spot
• Sunken cankers at the base of the trunk, progressive decline of the upper canopy: crown canker (Phytophthora)
• Small entry holes in the bark with sawdust frass, sloughing bark on the trunk: dogwood borer

Most dogwood disease problems trace to a stressed tree on a poor site. Dogwoods evolved as understory trees in moist forest soils. They struggle in full sun on poorly drained suburban lots, and that stress is what opens the door to anthracnose and crown canker.

Dogwood anthracnose

Dogwood anthracnose (Discula destructiva) is the most devastating disease in this guide. According to the Connecticut Agricultural Experiment Station, the pathogen was inadvertently introduced from Asia in the late 1970s. Because Cornus florida evolved with no natural defenses against the introduced fungus, the disease swept through eastern North America in the 1980s and continues to kill backyard and wild dogwoods today.

What it looks like

Initial leaf symptoms develop in May and June: brown spots up to a quarter inch in diameter, visible on both the upper and lower leaf surfaces, with distinctive smoky purple-brown margins. The spots often coalesce, killing larger sections of the leaf and producing scorched-looking foliage. Heavy infections cause early leaf drop, often by midsummer.

From the leaves, the fungus moves into the twigs and branches, producing small dark cankers that gradually girdle and kill the affected wood. Once the disease reaches the main trunk, it produces irregular dark cankers that progress over multiple years, eventually killing the tree.

Why it happens

The fungus overwinters in infected leaves and twig cankers. Spring rains release spores that infect new growth. Cool, wet, shaded conditions favor the disease. Trees in high-elevation forests, on north-facing slopes, and in moist mountain coves were hardest hit during the 1980s outbreak because the conditions there matched the fungus’s preferences.

Stressed trees are more susceptible than vigorous ones. Drought, soil compaction, root damage from construction, and poor planting all increase risk.

What to do about it

For an established Cornus florida showing early anthracnose symptoms, management aims to slow the disease and keep the tree alive long enough to enjoy it. There is no cure.

• Improve growing conditions. Mulch the root zone with 2-4 inches of wood chips (keep mulch 6 inches from the trunk). Water deeply during summer drought. Avoid fertilizing heavily, which produces susceptible new growth.
• Prune out dead and infected wood in late winter. Cut into clean wood several inches below visible cankers. Sterilize tools between cuts with 70% alcohol.
• Fungicide applications can help in early stages. Chlorothalonil or copper applied at bud break and again after leaf expansion suppresses new infections. Bonide Copper Fungicide at full label rate, applied in mid-April and again 14 days later, is the home-garden standard. Established disease that has reached the trunk cannot be reversed.
• Rake fallen leaves in autumn to reduce next year’s spore source.

How to keep it from coming back

For new plantings, cultivar choice solves the problem. Resistant species and cultivars:

• Kousa dogwood (Cornus kousa): Highly resistant. Blooms later than C. florida (June rather than April) and has rougher bark, but otherwise produces the same showy bracts and red fall color.
• Pagoda dogwood (Cornus alternifolia): Resistant native alternative with horizontal branching habit.
• Silky dogwood (Cornus amomum): Resistant shrub form, good for naturalistic plantings.
• Hybrid cultivars from the C. florida × C. kousa crosses bred at Rutgers: Aurora, Celestial, Constellation, Ruth Ellen, Stardust, and Stellar Pink. These look like C. florida but resist anthracnose.

For homeowners attached to Cornus florida specifically, the ‘Appalachian’ series cultivars (Appalachian Spring, Appalachian Joy, Appalachian Mist, Appalachian Snow) were bred by the University of Tennessee specifically for anthracnose resistance and represent the closest C. florida-form alternative.

For homeowners with site flexibility, our evergreen dogwood guide covers the Asian evergreen dogwoods (Cornus capitata, C. hongkongensis) that resist anthracnose completely and grow in zones 8-10.

Powdery mildew

Dogwood powdery mildew (Erysiphe pulchra, formerly Microsphaera pulchra) is the second most common dogwood disease. It hits hardest on stressed trees in poor air circulation. Per TN State Extension, the disease is most common in dense shaded areas where air circulation is poor, with warm days and cool damp nights driving the worst outbreaks.

What it looks like

A fine white powdery coating on the upper leaf surface, usually appearing first on the youngest growth. Severe infections cause:

• Marginal leaf scorch (browning at leaf edges)
• Dead patches in the leaf tissue
• Reddish discoloration on infected leaves
• Yellowing and premature defoliation
• Stunted shoot growth

Unlike anthracnose, powdery mildew doesn’t kill the tree, but repeated severe infections weaken it and make it more vulnerable to other problems.

Why it happens

The fungus overwinters in dormant buds and on bark surfaces. Spring temperatures around 70-85°F with high humidity at night create ideal conditions. Young, succulent growth is the most susceptible target. Dense plantings, shaded sites, and trees in poor air circulation get hit worst.

What to do about it

• Open the canopy by pruning out crossing branches and crowded interior growth in late winter. Better airflow alone solves many cases.
• Move overhead spray irrigation away from the canopy. Wet leaves at dusk are the worst-case condition.
• Neem oil applications: Bonide Neem Oil concentrate sprayed at the first sign of mildew, then repeated every 7-14 days through the growing season, suppresses active infections. Spray the underside of leaves, not just the top.
• For severe recurrent cases, propiconazole or triadimefon (commercial products) are more effective than neem, but for a backyard dogwood, neem is the safer home-grower starting point.

How to keep it from coming back

Cultivar resistance varies. The same Rutgers Stellar series and University of Tennessee Appalachian series that resist anthracnose also resist powdery mildew. Kousa dogwood is moderately resistant. Older common Cornus florida varieties (Cherokee Chief, Cherokee Brave, White Cloud) are highly susceptible.

Septoria leaf spot

Septoria leaf spot (Septoria cornicola) is a fungal disease that hits dogwoods in mid to late summer. Small angular dark spots with purple borders develop on the leaves, often only a few millimeters across. Heavy infections cause yellowing and early leaf drop in August and September.

The disease is cosmetic on healthy trees. Premature defoliation reduces the carbohydrates stored for winter but rarely kills the tree by itself. Leaves drop early either way, just a few weeks before normal autumn senescence.

What to do about it

For most backyard dogwoods, septoria leaf spot is not worth chasing with fungicide. Two passive controls handle it:

• Rake fallen leaves in autumn. Septoria overwinters in leaf litter.
• Improve air circulation with selective interior pruning.

If septoria coincides with active anthracnose or powdery mildew, the same copper or neem applications that target those diseases also suppress septoria. For backyard trees with septoria alone, intervention is rarely justified.

Crown canker

Crown canker (Phytophthora cactorum) is the second most likely disease to kill a flowering dogwood. The pathogen attacks the bark at the soil line, gradually girdling the trunk over 2-3 years. By the time symptoms appear above ground, the disease is usually advanced.

What it looks like

Early symptoms include diminished vigor: smaller leaves, lighter green coloring, sparser canopy, and early autumn color (a stressed dogwood will turn red in August rather than October).

At the base of the trunk, the inner bark, cambium, and sapwood become discolored. As the canker progresses, the affected area sinks and the bark falls away, exposing dark wood underneath. Eventually the canker girdles the trunk or root crown, and the tree dies.

Unlike anthracnose lesions on twigs and branches, crown canker is concentrated at the soil line and lower trunk. Look for the symptom by gently scraping bark with a knife at the soil line in suspected trees. Healthy bark scrapes back to light cream or light green tissue. Diseased bark reveals dark brown or black wet tissue underneath.

Why it happens

The pathogen is a water mold (Phytophthora, similar to citrus brown rot and foot rot). It lives in soil and infects through wounds in the bark, especially wounds caused by mowers, string trimmers, or construction equipment near the trunk base. Overhead irrigation that wets the trunk during cool weather provides ideal infection conditions.

Mulching too deeply (mulch volcanoes) and grading soil up against the trunk both create the moist bark conditions Phytophthora needs.

What to do about it

Once crown canker is established, the tree is usually finished. Catching it early allows for some intervention.

• Surgery on small cankers: in dry weather, use a sharp clean knife to remove diseased bark plus a 1-2 inch buffer of healthy tissue. Leave the wound exposed to air. Do not cover with soil, mulch, or wound dressing.
• Pull mulch and soil away from the trunk. Maintain at least 6 inches of bare soil around the base.
• Stop overhead irrigation that wets the trunk.
• Apply fosetyl-al or copper fungicide to the exposed wound and the surrounding soil. This is suppressive, not curative.

If the canker has girdled more than half the trunk circumference, the tree won’t recover. Plan for replacement with a resistant Cornus kousa or hybrid cultivar on a better-drained site.

How to keep it from coming back

Prevention is the entire strategy:

• Plant on well-drained soil. If drainage is questionable, plant on a raised mound 6-8 inches above grade.
• Keep mulch 6 inches from the trunk
• Don’t bump the trunk with mowers or trimmers. A 4-foot mulched ring around the tree prevents most mower damage and reduces dogwood borer incidence at the same time.
• Use drip irrigation at the root zone, not overhead spray.
• Pick Cornus kousa or a C. florida hybrid for new plantings on borderline sites.

Dogwood borer

Dogwood borer (Synanthedon scitula) is the most damaging insect pest of flowering dogwoods, but it almost never attacks healthy trees with intact bark. The borer requires a wound to enter, which is why the same maintenance habits that prevent crown canker also prevent dogwood borer.

What it looks like

• Small entry holes in the bark of the main trunk and larger branches, sometimes with sawdust-like frass extruded
• Sloughing bark that pulls away from the trunk in patches
• Top dieback of the canopy as the larvae girdle the cambium internally
• Adventitious growth: sprouts emerging from the trunk and main branches as the tree tries to compensate for damaged conducting tissue
• Loose bark on the trunk, sometimes an early warning before other symptoms appear

The damage is done by the larvae of a clearwing moth that resembles a yellow-and-black wasp as an adult. The adult moth lays eggs on bark wounds, especially at the soil line and on lower branches.

Why it happens

The borer needs a bark wound to enter. Common wound sources:

• Mower or string trimmer damage at the soil line
• Mechanical injury from construction equipment or pruning
• Sunscald cracks on the south or southwest side of the trunk
• Crown canker entry points (which is why borer and Phytophthora often appear together)
• Recent pruning cuts on larger branches

A dogwood with smooth intact bark and a mulched ring around the trunk is largely invisible to dogwood borer. A dogwood with mower damage near the soil line is a target.

What to do about it

For trees already infested:

• Place bark mulch around the base of the tree to suppress weeds and eliminate the need for mowers near the trunk. This is the single highest-leverage prevention.
• Insecticidal control: a long-residual insecticide applied to the bark in early April catches the egg-laying adults. A second application in late May may be necessary in heavy-infestation regions. Permethrin-based products are common; check the label for “borer control” on dogwood.
• Entomopathogenic nematodes: beneficial nematodes (Steinernema species) applied to infested bark can reduce larval populations.
• Paint fresh bark wounds with white latex paint to discourage egg-laying. Old-fashioned but effective.

How to keep it from coming back

The borer is a symptom of poor maintenance more than a disease problem. Trees with:

• Mulched rings 4+ feet wide around the trunk
• No mower or trimmer contact with the bark
• Whitewashed lower trunks (1:1 latex paint with water) in regions with sunscald risk
• Good vigor from proper watering and fertilization

…rarely attract dogwood borer in significant numbers.

When to call an arborist

Three situations warrant a professional visit on a dogwood. First, a mature Cornus florida (20+ years) showing trunk symptoms where you can’t distinguish between anthracnose cankers, crown canker, and borer damage. The treatments differ and getting it wrong is expensive. Second, a tree with progressive decline across multiple branches where the underlying stress is unclear. Third, a high-value landscape dogwood where deciding between aggressive intervention and replacement matters financially.

An ISA-certified arborist consultation runs $75-200 in most US markets. Find one through the Trees Are Good arborist locator or read our guide to what an arborist does before you call.

If the tree is past saving, tree removal on a mature dogwood typically runs $300-1,200. The fact that dogwoods are small (15-30 feet) keeps removal costs lower than most yard trees.

Prevention checklist

Seven habits handle almost all dogwood disease problems:

• Plant resistant cultivars. For new plantings, choose Kousa dogwood, a Stellar series hybrid, or an Appalachian series Cornus florida cultivar. Disease-resistant cultivars require almost no intervention.
• Site for understory conditions. Dogwoods evolved in moist, well-drained forest soils with partial shade. Full sun on a poorly drained suburban lot is the stress profile that drives every disease in this guide.
• Mulch the root zone with 2-4 inches of wood chips, keeping mulch 6 inches from the trunk. Prevents mower damage, crown canker, dogwood borer, and drought stress in a single habit.
• Drip irrigate at the root zone. Avoid wetting the trunk and lower canopy during cool weather. Sprinklers are anthracnose’s best friend.
• Single dormant fungicide application in early spring at bud break. Copper or chlorothalonil targets anthracnose, septoria, and powdery mildew primary infections.
• Rake fallen leaves in autumn. Reduces overwintering inoculum for anthracnose, septoria, and powdery mildew.
• Don’t let mowers or trimmers touch the trunk. Single biggest source of dogwood borer infestations.

For broader fungal disease patterns across the rest of your yard, see our tree fungus guide. Looking for replacement options? Our spring flowering trees guide covers magnolia, redbud, and other small-tree alternatives that share dogwood’s role in the landscape. Our pink and purple flowering trees guide includes additional resistant alternatives, and the broader flowering trees roundup covers the full landscape category.

Frequently asked questions

What is the most dangerous dogwood tree disease?

Dogwood anthracnose (Discula destructiva) is the most dangerous and the one that killed millions of dogwoods across the eastern US in the 1980s and 90s. Crown canker (Phytophthora cactorum) is the second most likely to kill a tree. Powdery mildew, septoria leaf spot, and dogwood borer are manageable problems that rarely kill trees by themselves but weaken them over time.

Can I save a dogwood with anthracnose?

If you catch it early (leaf symptoms only, no trunk lesions), aggressive sanitation and proper site conditions can slow the disease for many years. Once anthracnose reaches the trunk and produces cankers, the tree’s long-term prognosis is poor. Plan for replacement with a resistant Cornus kousa or hybrid cultivar.

What’s the best dogwood for resistance to disease?

Kousa dogwood (Cornus kousa) is the most resistant species. Among Cornus florida-form trees, the Stellar series (Aurora, Celestial, Constellation, Ruth Ellen, Stardust, Stellar Pink) hybrids and the Appalachian series cultivars (Appalachian Spring, Joy, Mist, Snow) were specifically bred for resistance. Older C. florida varieties (Cherokee Chief, Cherokee Brave, White Cloud) are highly susceptible to both anthracnose and powdery mildew.

Why does my dogwood look stressed every summer?

Site conditions, almost always. Dogwoods are forest-understory trees that struggle in full-sun suburban locations with compacted soil, drought stress, and reflected heat from pavement. Most dogwoods in residential landscapes are planted on sites that are too sunny and too dry for the species. A 4-foot mulched ring, deep summer watering, and partial shade from a larger tree dramatically reduces summer stress.

Are dogwood diseases contagious to other trees?

The major dogwood diseases are largely dogwood-specific. Discula destructiva attacks dogwoods, primarily Cornus florida and C. nuttallii. Phytophthora cactorum (crown canker) can attack many tree species but the disease expression is different in each. Powdery mildew on dogwoods (Erysiphe pulchra) is a different species from the powdery mildew that hits other trees, so it doesn’t cross. Dogwood borer (Synanthedon scitula) is mostly dogwood-specific but can also attack pecans and apples in low numbers.

When should I spray my dogwood?

A Cornus florida in an anthracnose-pressure region (Appalachians, mid-Atlantic, Northeast forests) needs one fungicide application at bud break in mid-April and a second 14 days later, which covers most of the primary infection window. Kousa dogwoods and resistant hybrids almost never need spraying. For powdery mildew alone, spot-treatment with neem oil starting at first symptoms beats a calendar schedule.

Will a dogwood recover after losing all its leaves to anthracnose?

Once is recoverable. Three years in a row of total summer defoliation usually leads to trunk cankers and decline. The leaves drop, the tree pushes a smaller second flush of leaves a few weeks later, but the carbohydrate cost weakens the tree over multiple years. Trees that lose their leaves every summer for 4+ years are usually finished.

Should I cut down a dogwood with crown canker?

If the canker has girdled less than half the trunk circumference and the upper canopy still looks reasonably healthy, surgery and improved site conditions can extend the tree’s life for several years. If the canker has girdled more than half the trunk or the canopy is already showing significant decline, removal and replacement is the practical choice. A new Cornus kousa on a properly prepared site will exceed the declining tree’s beauty within 5-7 years.