The most serious fungal problem for potted plants is usually below the surface. Root rot is caused by organisms such as Pythium, Phytophthora, Rhizoctonia and Fusarium, which thrive in wet, poorly drained mix. Stressed, overwatered plants are easy targets.
Signs include lower leaves wilting and yellowing even though the mix is moist, and a darkened stem base. Rotted roots are brown to black and mushy. Move an affected plant away from the others. If the rot is severe, the University of Maryland advises discarding the plant and taking stem cuttings only from healthy tissue.
Above ground, you may see fungal leaf spots, brown spots often with a yellow halo, or powdery mildew, a white powdery coating. Remove affected leaves, improve air movement around plants and avoid splashing water onto foliage, which spreads spores. This matters in humid, still air, common in tropical homes.
Prevention does most of the work: well-drained mix, clean pots and careful watering.
Key points
- Root rot thrives in wet, poorly drained mix.
- Healthy roots are firm; rotted roots are brown and mushy.
- For leaf spots: remove affected leaves, add airflow, keep foliage dry.
Try this
Next time you repot or check a plant, gently look at a few roots and note their colour and firmness.
Check yourself
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Sources
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