Yellow Mold on Rock Mulch: Nuisance Fungus That's Harmless to Plants

Yellow/tan mold appears on red rock mulch (not wood mulch). It dries to tan during the day. Started in a low juniper, now on bare rocks.

No Threat to Plants

It's a slime mold—unsightly but benign.

Control

• Blast with hose whenever seen.
• Spring fungicide applications may reduce recurrence.
• Destroy each morning before it dries and releases spores.

Since it's harmless, aggressive treatment isn't necessary.