Root Maggot
White, legless quarter-inch larvae tunneling through the roots of cabbage-family crops, radishes, and onions. Above ground it reads as seedlings that wilt in the sun and stunt for no visible reason — pull one and the riddled root tells the story.
Pest checklist
Four things to look for. If most of them match what you are holding, you are in the right place.
What gets rid of them
Gentlest option first. For most backyard cases the first one is enough, so try these in order and stop as soon as it works. If you do spray something, the product label tells you how — please read the notice further down.
1Row cover at sowing
The fly lays at the stem base in spring; cover before she arrives and the crop never meets the maggot.
floating row cover gardenTry this first2Collars at the stem
A disc of cardboard or landscape fabric flat on the soil around each transplant blocks egg-laying at the stem.
3Rotate the family
Brassicas in a new bed each year leave last season's overwintering pupae emerging under the wrong crop.
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Which plants get root maggot
Every plant we cover that gets root maggot, grouped by type — tap any one to open its page. A note beside a plant came from that plant’s own entry, because the same pest can be a minor nuisance on one plant and a serious problem on another. Plenty of plants we do not cover get it too.
Plant families hit hardest
Related plants often share the same problems, so if one plant in a family has it, check the others. The largest group here is Brassicaceae, with 5 of the 5 affected plants.
- Brassicaceae5 plants
When to treat
This one is prevention. Cover the crop at sowing, because by the time plants wilt the roots have already been eaten.
Timing only — the label is the law
This page tells you when to watch for root maggot and when treating is worth considering. It is not a recommendation to apply any particular product. Read and follow the product label before you spray — under federal law the label is the legal instruction, and using a pesticide against it is illegal.
- Check the pre-harvest interval. Every product that’s cleared for an edible crop sets a minimum number of days between spraying and picking. Find it on the label before you spray anything you intend to eat.
- Check the re-entry interval before you or anyone else works in the treated area again, and use the protective equipment the label names.
- Confirm the product is registered for your crop in your state. This page groups many different crops together, and a product legal on one of them is not legal on all of them — state registrations differ too. Your state pesticide agency or local extension office can confirm both.
- Rates and mixing instructions come from the label, never from us. We don’t publish them because they differ by product and formulation.
Other problems on the same plants
If a plant gets root maggot, these are the problems it most often gets as well, so they are worth checking for while you are out there. They tend to appear together; one does not cause another.