Saving an Overwatered Dieffenbachia from Fungal Rot

The "cancer-like" brown spots, orange discoloration spreading from leaf tips, and your watering setup (moisture-control soil + aqua globe) point to one clear culprit: chronic overwatering leading to fungal infection.

Why It's Happening

Dieffenbachia needs to dry out between waterings. Your combo keeps the soil constantly soggy—a perfect breeding ground for fungus. The roots are likely rotting.

Immediate Rescue Steps

1. Remove the aqua globe entirely.
2. Empty the drainage tray completely.
3. Let the soil dry out until the pot feels light.
4. Treat fungus: Lightly spray soil surface and leaves with Lysol (or a copper-based fungicide) every other day until soil is dry, orange color fades, and new growth appears.

Future Care

• Water only when top 1–2 inches of soil are dry.
• Use a well-draining mix (add extra perlite).
• No more self-watering devices for this plant.

It will recover with drier conditions. Good luck!