Bacterial Crown Rot After Repotting in Fine Bark: Physan 20 Rescue

Diana repotted multiple orchids in a fine bark mix from Home Depot. All yellowed, roots rotted. She reverted to her old coarse mix but then developed liquefying centers (crown rot)—leaves turning to liquid in the plant crown.

Diagnosis: Bacterial Crown Rot

Caused by water trapped in the crown during watering, especially late in the day. Fine bark mix likely held too much moisture, exacerbating the problem. The initial root rot was from the unsuitable mix; crown rot is a new, aggressive infection.

Emergency Protocol

1. Unpot immediately.
2. Soak entire plant in Physan 20 solution (1 Tbsp/gallon) for 10 minutes.
3. Repot in fresh, coarse fir-bark mix (soaked).
4. Withhold water 1 week.
5. Spray weekly with Physan 20 (per label).
6. Water early in day only—crown must dry by nightfall. Use a fan on watering days.

Mix Warning

Home Depot/Lowe's carry Miracle-Gro (fine, with fertilizer) and Better-Gro (coarse fir bark, AOS-recommended). Always choose coarse fir-bark-based mix. Soak before use.