The common problems with flowering dogwood fall into five categories. You'll deal with anthracnose, dogwood borer, powdery mildew, leaf scorch, and stem canker. Most of these issues start when your tree gets stressed. A dogwood in the wrong spot or without enough water will attract trouble far faster than a healthy one.
I found my first anthracnose case after I spotted tan blotches with purple edges on a neighbor's dogwood. We thought it was drought stress at first. But the spots kept growing and branches died back from the tips. A few weeks later I found a different dogwood down the street with wilting on one side only. In my experience, that pattern meant borer damage. Sure enough, I found sawdust piled at entry holes near the trunk base. Same species, same block, two different problems.
Flowering dogwood diseases cause the widest damage. Anthracnose from Discula destructiva has caused a 49% drop in wild dogwood numbers. Cool, wet springs give the spores ideal conditions to hop from leaf to leaf on your tree. Powdery mildew coats your foliage with white dust that blocks light. The worst threat per USDA research is Phytophthora root rot, which attacks trees in soggy soil and can kill yours fast.
Flowering dogwood pests target trees that are already weak. Dogwood borer larvae enter your trunk through wounds from mowers or string trimmers. Once inside, they feed on living tissue for up to two years before they emerge. Club gall midge creates small tube-like growths on your twig tips that stunt new growth. Scale insects drain sap and leave sticky residue that attracts sooty mold to your branches.
Stress ties all these problems together for your tree. Drought drops your tree's defenses against borers. Crowded plantings trap moisture on your leaves and feed fungal infections. Full sun heats up the thin bark and creates the sunscald wounds that borers use as entry points. Fix your tree's growing conditions and you block most threats before they start.
Your Monthly Check Routine
- Scan your leaves: Look for tan spots with purple margins on lower branches, which signal anthracnose before it spreads up through your canopy.
- Check the trunk base: Search for sawdust-like frass near soil level that tells you borer larvae are feeding inside your tree's trunk.
- Watch for white film: Powdery mildew shows up as a dusty white coating on your leaf surfaces during humid weeks in summer.
Disease Control Actions
- Prune infected branches: Cut back to healthy wood at least 6 inches below the symptoms and clean your pruners between each cut.
- Spray at bud break: In areas with known anthracnose, apply a copper-based fungicide as your buds start to open in early spring.
- Fix your drainage: If soil stays wet after rain, add organic matter or redirect water flow so Phytophthora root rot can't take hold.
Reduce Your Tree's Stress
- Keep a mulch ring: Maintain a 3 to 4 foot circle of mulch around your trunk to block mower damage and hold moisture for your roots.
- Water through dry spells: Give your tree 1 inch per week in July and August to keep it strong enough to resist borers on its own.
- Ensure partial shade: Your tree in full sun will suffer more bark damage, more heat stress, and more pest attacks than one in filtered light.
I also learned the hard way that you should never ignore leaf scorch on your dogwood. I tested waiting it out one summer, thinking the rain would come back. By September that tree had dropped half its leaves. The stress opened the door for borer damage the next spring. Now I run a soaker hose at the first sign of brown edges. You should do the same if your tree starts showing scorch marks in July or August.
Stay ahead of the common problems with flowering dogwood by keeping your tree healthy from the start. A strong tree in the right spot with steady water fights off most threats on its own. Your best defense is a well-planted, well-watered dogwood that never gets stressed enough to let trouble in.
Read the full article: Flowering Dogwood: Complete Guide
