Dogwood trees are vulnerable to several fungal diseases, and the key to identifying which one you’re dealing with lies in the leaf spots, bark changes, and pattern of decline. Most dogwood fungal problems show up first on the leaves, each with a slightly different color and border that acts like a fingerprint. Here’s how to tell them apart and what to do about them.
Dogwood Anthracnose: The Most Serious Threat
Dogwood anthracnose is the disease most likely to kill your tree. It starts as small tan spots on the leaves with a distinctive purple border where dead tissue meets healthy tissue. These spots can expand to consume entire leaves, and here’s the telltale sign: dead leaves cling to the tree instead of falling. During bloom, you may also see those same tan-and-purple spots on the flower bracts.
What makes this disease dangerous is that it doesn’t stop at the leaves. The fungus moves into the leaf stems and twigs, creating tan to brown blotches that can girdle (completely encircle) a branch and kill it. Over time, you’ll notice lower branches dying first, and clusters of small shoots sprouting near the base of the trunk. These shoots, called water sprouts, are the tree’s desperate attempt to replace lost foliage. Without intervention, the disease can kill the entire tree.
Spot Anthracnose: Ugly but Not Deadly
Spot anthracnose looks similar at first glance, which is why people confuse the two. The spots are small, dark, pinprick-sized lesions with purple borders, and they appear on dry leaves rather than wet ones. They’re usually numerous, giving the leaf a speckled appearance. The critical difference is that spot anthracnose never spreads to the branches. It stays on the leaves and flower bracts only. It makes your tree look rough, but it won’t kill it.
If you’re trying to decide which anthracnose you’re seeing, check the twigs and lower branches. Dead clinging leaves plus twig dieback means the serious form. Speckled leaves with no branch damage means spot anthracnose.
Cercospora and Septoria Leaf Spots
Two other common leaf spot fungi hit dogwoods, and they look quite similar to each other. Cercospora leaf spot produces tan to brown spots with yellow borders. Septoria leaf spot creates darker brown or purple spots with more prominent, well-defined borders. Neither is as destructive as dogwood anthracnose, but heavy infections can weaken a tree over multiple seasons.
The yellow border is your best clue for Cercospora. If the spots are darker and the borders look sharp and pronounced, you’re more likely looking at Septoria. Both tend to appear in mid to late summer when humidity is high.
Crown Canker: A Disease That Hides on the Trunk
Crown canker (also called collar rot) is sneaky because the early signs look like general stress rather than a specific disease. Your tree produces smaller, paler leaves than usual and drops them early. One counterintuitive clue: the tree may bloom heavily, producing an unusually large number of flowers. This is a stress response, not a sign of health.
The real evidence is on the lower trunk, usually near the ground line. Look for a darkened, discolored area of bark that may be weeping dark fluid. This canker expands over time, eventually girdling the trunk. By the time you notice the canker, the disease is often well established. Crown canker is caused by a water mold that thrives in wet soil, so poorly drained planting sites are a major risk factor.
Armillaria Root Rot: Check Below the Bark
Armillaria root rot attacks from underground, and the aboveground symptoms overlap with many other problems: smaller leaves, yellowing, leaf drop, branch dieback. What sets it apart is what you find when you look closer. Peel back a section of bark near the base of the trunk, and you may see white, thread-like fungal mats growing underneath. At the soil surface or just below it, look for dark, shoestring-like strands spreading outward from the trunk.
In fall, honey-colored mushrooms often appear in clusters near the base of infected trees. That’s one of the most definitive signs. You may also notice a dark black line in the wood encircling the base of the plant, visible if you cut into the bark. Armillaria is essentially untreatable once established, so identification matters mainly for deciding whether to remove the tree and what to plant in its place.
Fungal Disease vs. Drought Stress
Brown, crispy leaf edges can look alarming, but they don’t always mean fungus. Drought stress and leaf scorch cause browning that starts at the leaf margins and tips, then moves inward. The browning is uniform, without distinct spots or colored borders. Fungal leaf spots, by contrast, appear as discrete, round or irregular patches with visible borders in purple, yellow, or reddish tones scattered across the leaf surface.
If you see spotting with colored halos anywhere on the leaf blade (not just the edges), that’s fungal. If the browning is confined to the outer edges and there’s been recent heat or dry weather, drought is the more likely culprit.
Managing Fungal Infections
Cultural care is your first line of defense and often the most effective. Prune out all dead or dying twigs and branches during dry weather, including any water sprouts on the trunk. In fall, rake and remove fallen leaves, and pull off any dead leaves still clinging to branches. Both steps reduce the amount of fungal spores available to reinfect the tree the following spring.
During dry spells, give your dogwood a deep soaking at the root zone and maintain two to three inches of composted mulch. Avoid heavy fertilization, which pushes soft new growth that’s more susceptible to infection. Adequate sunlight and good air circulation around the canopy also help leaves dry quickly, which discourages fungal growth.
For anthracnose specifically, fungicide sprays can protect new growth if applied at bud break and repeated every 10 to 14 days until leaves are fully expanded. A final spray in fall, after leaves change color but before they drop, helps reduce overwintering spores. Look for products containing propiconazole or chlorothalonil at your garden center. Alternating between different types prevents the fungus from developing resistance.
Resistant Varieties Worth Planting
If you’re planting a new dogwood or replacing one lost to disease, choosing a resistant variety saves years of trouble. Kousa dogwoods and their hybrids with native flowering dogwood have shown strong resistance to anthracnose. In university trials, Stellar Pink, Celestial, and Stardust hybrids all had 1% or less leaf area affected and 100% survival, with no fungus detected in their woody tissue.
For powdery mildew resistance (another common fungal problem on dogwoods), kousa cultivars like Milky Way, Gay Head, Julian, and China Girl performed well. The hybrids Stellar Pink, Celestial, and Aurora showed resistance to both anthracnose and powdery mildew, making them especially good choices if fungal diseases are common in your area. Avoiding wild-collected native dogwoods and choosing nursery-grown resistant cultivars is one of the simplest ways to prevent problems before they start.