If the tops of your carrot plants are green, the roots have been exposed to sunlight. Cut away the green part of the root, and the rest can be eaten. For carrots still in the ground, cover exposed roots with soil or mulch.
Roots hairy, forked, misshapen
Plant carrots in loose, evenly moist, not soggy, soil. Thin plants as they grow to avoid overcrowding.
Read more about management of nematodes.