Pythium Crown Rot in Dwarf Mondo Grass: Diagnosis and Fungicide Treatment

Browning, easily pulled leaves in established dwarf mondo grass during extreme heat (60+ days over 100°F) suggest Pythium crown rot. Certain Pythium species are active at high temperatures.

Confirming Pythium

• Roots/crowns brown-black, possibly slimy with foul odor.
• Environmental stress alone leaves roots light-colored and intact.

Management

1. Remove and destroy severely infected plants and surrounding soil.
2. Do not replant with mondo grass.
3. Treat marginally affected plants with a fungicide drench: Aliette (fosetyl-Al) or Subdue (mefenoxam).
4. Water early in the day so foliage dries before night.

See fact sheet (page 3) for images: plantpathology.uark.edu/Number3-2009.pdf