Brown Rot or Root Rot
Root rot happens when the medium degrades, the drainage is inadequate, or the plants are overwatered. When roots suffer damage from trauma, salt accumulation from hard water, or excessive fertilisation, rot occurs and Rhizoctonia solani fungal levels rise to deadly levels. Rhizoctonia in cattleyas steadily progresses from the older to the younger pseudobulbs and up the pseudobulb, which eventually turns brown and hard and becomes husky. Older, diseased sections of the plant lose their roots.
Symptoms
Brown rot or root rot is caused by Rhizoctonia. The aerial sections of the plant might exhibit signs that resemble Fusarium damage. Older pseudobulbs turn brown from the bottom up and eventually drop their leaves.
Treatment
Treating orchid diseases at the roots requires removal of the plant from its medium and using a sterile cutting tool to cut off infected leaves, roots and leaves. Then use a fungicide to drench the roots for 15 to 20 minutes and clean the growing area with Hydrogen Peroxide diluted with water at a 1:10 ratio.
Following Fungicides are effective:
- Chemical name: Thiophanate methyl (Brands: Roko) | Dosage: 1g/L of water
- Chemical name: Combimnation of Boscalid and Pyraclostrobin (Brand: Signum, Visma etc.) 1g/L of water
Once the plants are repotted, water the plants only if required. Keeping the plants drier will help to keep the infection from spreading or appearing again. Isolate the plants and observe the plants for 1-2 weeks. And apply another round of control spray with any of the above fungicides. Spray the plants early morning and keep the plants dry after the spraying. Don't water the plants same-day on which the spray treatment is done.
Prevention
- Avoid Over-watering
- Provide good air circulation
- Frequent Inspection of plants
- Isolation of suspicious plants
- Precautionary control sprays
