Rhizoctonia root rot of horseradish
Rhizoctonia solani
What you will see
On the cuttings (side roots) and on the main roots there are round to oval sunken dark brown spots ¼–¾ in, with white fungal mycelium in damp conditions; they may be cracked or canker-like thickened. Yield loss up to 30%.
How to protect
- Prevention
- Keep to a crop rotation of at least three years; the fungus attacks many other crops.
- Cooler, quick-drying soils reduce infection.
- Side roots are the planting material for the next year, so the disease spreads through planting stock.
