Answer: Your radishes are probably home to wireworms, the larvae of a fly. They also attack other root crops, like carrots and turnips. The best defense is to place a barrier between your plants and the adult fly so she can't lay her eggs next to the developing root crops. Radishes, carrots and turnips don't need pollination from insects, so you can plant your crops and cover them with a floating row cover (like Reemay) to exclude the insects. Make sure that you anchor the floating row cover material down tightly. I use pieces of wire or bent coat hangers, dig a shallow trench around the garden spot, place the end of the row cover (pulled tight) in the soil, anchor with wire, and cover the trench in. The insects can't access the soil or plants, and the root crops develop into tasty, insect-free produce.
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