White mold on orchids

White mold on orchids is a common issue faced by growers. It can appear on roots, substrate, leaves, or even flower spikes, indicating overwatering, poor ventilation, or fungal spore contamination. To eliminate the mold and prevent its recurrence, it's essential to identify the cause and take appropriate measures.

Why does white mold appear?

1. Excessive watering:
   • Consistently wet substrate creates ideal conditions for fungal growth.
2. Poor ventilation:
   • Lack of air circulation in the environment promotes mold development.
3. Compacted or decomposed substrate:
   • Old substrate loses its drainage properties and retains excess moisture.
4. High humidity:
   • Humidity above 70% without proper ventilation encourages mold growth.
5. Spore contamination:
   • Using contaminated substrate or placing the orchid near infected plants.

What to do if white mold appears?

1. Remove the mold:
   • From leaves and flower spikes:
     wipe affected areas with a soft cloth dipped in a fungicide solution or soapy water.
   • From roots:
     remove the plant from the pot, rinse the roots under running water, and cut off infected parts with sterile tools.
   • From the substrate:
     discard the contaminated substrate and replace it with fresh material.
2. Fungicide treatment:
   • Use a broad-spectrum fungicide suitable for orchids.
   • Dilute the product as directed and treat both the plant and the substrate.
3. Rinse the roots:
   • Soak the orchid’s roots in a weak solution of potassium permanganate or hydrogen peroxide (1 tablespoon per liter of water) for 10–15 minutes.
4. Repotting:
   • If mold has spread to the substrate, repot the orchid into fresh, high-quality substrate.
   • Ensure the new pot has drainage holes to remove excess water.
5. Improve growing conditions:
   • Watering: only water once the substrate has completely dried out.
   • Ventilation: ensure good air circulation around the plant.
   • Light: place the orchid in a well-lit spot with indirect sunlight.

Preventing white mold

1. Control watering:
   • Water the orchid only when the substrate is completely dry.
   • Use soft, room-temperature water.
2. Refresh the substrate:
   • Replace the substrate every 1.5–2 years. Use high-quality materials like pine bark or coconut chips.
3. Maintain humidity and ventilation:
   • Keep humidity levels at 50–60%.
   • Use fans or humidifiers with an air circulation feature.
4. Apply preventative treatments:
   • Regularly spray the orchid and substrate with a weak fungicide solution.
5. Inspect plants:
   • Periodically check the orchid for mold or pests to address issues early.

Conclusion

White mold on orchids is a sign of improper care. Regular maintenance, proper watering, and timely substrate replacement can help prevent mold. If mold has already appeared, follow these recommendations to address the issue quickly and effectively.