The best solution for me has been floating row cover. It gives 100% protection when installed soon as seeds are planted and kept in good contact with the ground around the edges. Using pesticides on root crops makes me uneasy. I think there must be some residue in the roots.

Jim

Diatomatious earth, I think, would not work since it has to be kept dry to be effective. Also, DE kills all insects whether beneficial or pests.

Jimster's suggestion sounds good.

Agribon insect barrier (one of several brands of floating row covers) is available at Johnny's, Maine, and at Peaceful Valley Farm, CA, but you might find it at your local farm store and save on shipping.

Row covers are available in various fabric weights. The lightest are used against insects, the heavier ones to protect against frost.

Hope this is useful.