Sparse Leaves on a Flowering Lilac: Could It Be Armillaria Root Rot?

Symptoms: Abundant Flowers, Few Leaves

A five‑year‑old lilac in northeast Ohio blooms heavily but has very sparse foliage, while neighboring lilacs look normal. The leaves present appear healthy, and there’s no obvious insect damage.

Diagnostic Checklist

• Scratch the bark: green underneath means living tissue.
• Check for trunk damage at ground level.
• Look for honey‑colored mushrooms at the base in late summer/fall (sign of Armillaria mellea).
• Note any recent root disturbance, construction, or herbicide use nearby.

Armillaria Root Rot Suspected

Lilacs are highly susceptible to Armillaria (honey fungus). The fungus kills roots, reducing water uptake, so the tree puts energy into flowers (already set the previous year) but cannot support a full canopy. The expert provided university links for confirmation.

Next Steps

If Armillaria is confirmed, there is no cure. Remove the tree and avoid replanting susceptible species in the same spot. Improve drainage and avoid wounding roots of nearby plants.