Black Patches on Orchid Leaves: Sunburn, Bacteria, or Fungus?

Black areas on orchid leaves have three main causes:

• Sunburn: Irregular blotches after intense afternoon sun. Increase shading.
• Bacterial/fungal disease: Spots enlarge over time. Cut out diseased tissue with sterile tool; treat with Physan 20 or copper fungicide.
• Black leaf tips: From hard water, over-fertilizing, or fungus. Flush pot monthly with plain water; trim black tips with sterilized scissors.

Misting the crown invites rot. Water at base only, provide bright indirect light, and maintain air movement.