Mode of spread and survival:
- Damping-off of carrot seedlings and a crown rot later and during storage
- Field symptoms include premature senescence and death of foliage
- On carrot roots - dark brown sunken lesions or cankers near the crown or in other parts of the root – cavity spot
- Sclerotia - irregular, brown to black and 5mm in diameter
- Fungus produces both terminal and intercalary, barrel shaped chlamydospore
- R. solani overwinters in soils as mycelia on plant debris and as dark brown sclerotia that remain in soil for long periods
- R. solani can spread from plant to plant in closely spaced carrots when the canopy is fully formed
- More severe on muck-grown carrots
- Warm temperatures and wet conditions - especially when these environmental conditions occur near harvest
Management :
- Cultural practices that reduce crown injury and enhance soil drainage and air circulation within the canopy are recommended
- Plant debris from previous crops should be removed before planting carrots
- Carrots should not follow perennial crops such as alfalfa
- Quintozene – sprayed in the soil before sowing-effective control
| Initial symptom | Dark Brown sunkern leisons | Infected carrots |