Maggots.

Nature Published in 1908 by the U.S. Department of Agriculture, Bureau of Entomology, Root-maggots and how to control them is a handy guide to deal with one of nature's scariest pests listing ever more invasive procedures:

"Hand picking, although laborious, has the merit of being effective, and is practised with considerable success by extensive cabbage growers, although not practicable on radish and similar crops. It consists in pulling up the young cabbage or cauliflower plants, examining the roots for eggs and maggots, and either destroying the eggs and maggots by crushing with the hand or by washing the roots in a strong solution of soap and then replanting. In most cases the plants show no ill effects from this treatment after two or three weeks have elapsed. By looking closely, the minute white eggs may be seen about the stalks of young cabbages, and if the earth be raked away so as to expose the eggs to the sun these will dry up, thus preventing the maggots from hatching. Afterwards the plants should be hilled."

No. Just no.  Ick.