Plants Are Stunted Because Of Root Knot Nematodes.

If carrot plants are stunted and their leaves are yellow, suspect root knot nematodes. Nematodes are almost microscopic soil-dwelling roundworms that burrow into a carrot’s fine root hairs and interfere with their uptake of nutrients, causing little nodules or galls (and an unsightly carrot) to form. They are a problem particularly in the South.

For complete information see the file Controlling Destructive Nematodes