Lambs Ear Leaf Rot
Opportunistic rot fungi (Sclerotium, Rhizoctonia, and Botrytis species)
A moisture-driven foliar and crown rot of lamb (lambs) ear, in which the dense, woolly, water-holding leaves stay wet and the foliage in the center and base of the clump turns to a matted, rotting mush. It is mainly a problem of culture and conditions, worst in hot, humid, rainy weather and crowded, poorly drained plantings.
🔎 How to spot it
The first sign is matted, blackened, rotting foliage in the middle of a large clump or underneath the leaves where air does not reach, often after heavy rain or in a humid summer. Affected leaves go soft, brown to black, and slimy and collapse, and the clump can melt out in patches (crown meltout). The fuzzy, moisture-trapping leaves also invite powdery mildew and leaf spots in the same wet conditions.
🥀 Damage it causes
Patches of the planting rot out and die, leaving bare, mushy gaps in the clump, and a badly affected plant can largely collapse in a wet spell. The plant usually regrows from the healthy edges once conditions dry, so the damage is more disfiguring than fatal, but it sets the planting back.
🔬 What causes it
It is primarily a cultural problem: moisture accumulating from excessive rain, overhead watering, poorly drained soil, and overcrowding keeps the woolly foliage wet so it rots. Opportunistic rot fungi (such as Sclerotium, Rhizoctonia, and Botrytis species) move into the constantly wet, matted tissue and speed the breakdown, especially in hot, humid weather.
🛡️ Prevent it
Grow lamb ear lean and dry: full sun, sharp drainage, and plenty of space for air to move through the clump. Water at the base rather than over the leaves, avoid overcrowding, and thin or divide overlarge clumps in midsummer to open them up. Clearing matted old leaves keeps moisture from building in the center.
🧯 If it is already here
There is no spray needed in most cases; the fix is to gently clean out the rotting foliage as soon as it appears, divide crowded clumps, and improve drainage and airflow, which usually resolves the problem. Replant divisions on a sunnier, better-drained spot if rot keeps recurring.
💡 Good to know
Because the rot follows wet, crowded conditions, opening up the planting and keeping water off the woolly leaves does far more than any fungicide. It is the same moisture that brings on powdery mildew, so the cultural fixes solve both at once.
🌱 Plants it affects
13 plants in the library can be affected by this problem
For educational and informational purposes only. Disease management advice is general guidance drawn from university cooperative extension sources; always identify a problem positively and read and follow the label on any product before use, especially around food crops, children, and pets.