Powdery Mildew on Zucchini: Lime Sulfur or Copper Soap

Diagnosis

White powder spreading on leaves = powdery mildew. Sevin (insecticide) won’t touch it.

Treatment

• Lime sulfur – broad fungicide, garden centers.
• Soap Shield (copper soap) – organic, sticks better, Gardens Alive.

Reference

OSU fact sheet.