Introduction
Most “mystery declines” indoors come from a short list of diseases: fungal leaf spots, powdery mildew, gray mold (Botrytis), root rot, and bacterial leaf spot/soft rot. Learn to recognize their visual signatures and you can act fast with pruning, airflow, and targeted treatments.
1) Fungal diseases you’ll actually see
Powdery mildew looks like flour dust on leaves and stems. Leaf spots start as tan/brown circles with darker rims; they may coalesce. Gray mold (Botrytis) appears as fuzzy gray growth on wounded or senescing tissue, especially in cool, stagnant air.
Know More: Common Fungal Diseases Indoors — Identification & Treatment2) Root rot (the silent killer)
When soil stays wet, oxygen drops and pathogens take over. Leaves yellow from the bottom, stems soften, and the root ball smells sour. Healthy roots are firm and pale; rotten roots are brown/black and mushy.
Know More: Root Rot — Diagnosis & Step-by-Step Rescue3) Bacterial leaf spot & soft rot
Bacterial spots are water-soaked, irregular, sometimes translucent; soft rot turns tissue mushy and foul-smelling, spreading quickly in warm, wet conditions.
Know More: Bacterial Leaf Spot & Soft Rot — Symptoms & Control4) The universal fix kit
- Prune & dispose infected tissue (don’t compost indoors).
- Improve airflow: space plants, run a small fan on low, avoid crowded leaves.
- Water smarter: at soil level in the morning; let the mix partially dry between waterings.
- Sanitize tools & pots: alcohol or diluted bleach for shears and reused containers.
5) When to treat vs. replace
Minor outbreaks respond to cultural fixes + a mild fungicide (e.g., copper, sulfur, or bio-fungicides). Advanced bacterial mush or systemic decline may warrant discarding the plant to protect the collection.
Conclusion
Most indoor disease problems are preventable with airflow, clean tools, and right-time watering. Identify the pattern, act decisively, and your plants will bounce back.
