Diagnosing White Powder on Bare Soil: Salt or Fungus?

What Is That White Crust on Your Lawn?

A white powder on dry soil in a bare patch could be salt accumulation or powdery mildew fungus.

Quick Field Test

• Taste test: Wet a finger, touch the powder, touch tongue. Salt tastes salty; fungus does not.
• Soil test: Send a sample to your county extension agent for definitive analysis.

If It's Salt

Leach by flooding the area repeatedly (like flushing a houseplant). Past owners may have used salt to suppress vegetation. Solarization (black plastic on hot days) sterilizes soil but won't remove salt.

If It's Fungus

Spray with fungicide or baking soda solution (1–2 tbsp/gal water). Powdery mildew favors damp, shaded conditions—improve air flow and reduce moisture.

When in Doubt

Consult a local nurseryman or extension agent. They know regional soil issues and can recommend the right fix.