How to Get Rid of Cabbage Root Maggots | Quick Guide on Organic Control Methods

Cabbage root maggots, or Delia radicum, are potentially ruinous cool-season pests that enjoy feeding on the roots of plants ranging from cabbages to radishes. They can be hard to spot without digging and harder still to eject from your garden, but there are a number of organic and conventional prevention and treatment techniques that can help you save your crop.

What are cabbage root maggots?

Cabbage root maggots are the larvae of the cabbage root flies, which lay their eggs near the stem and soil around young plants in early spring.

Symptoms of root maggot infestation

Because the maggots themselves feed under the soil, your first sign of infestation usually won’t be a root maggot sighting. Instead, you’ll see wilting leaves that may display a bit of discoloration. Eventually, the entire plant will likely stop growing and die.

How to prevent root maggots

While no method is a 100-percent effective means of keeping root maggots (or root flies) at bay, there are a few ways to lower your chances of an uncontrollable infestation.

Plant later in the season

Since cabbage root flies will usually sow their eggs in early spring, one of the easiest ways to prevent initial exposure is by waiting until late spring or early summer to transplant.

Use row covers

Using row covers prevents initial exposure by keeping the root flies from planting their eggs on your young plants. The technique is much less effective when a prior infestation has happened in the same garden bed, as the overwintering maggots can work their way back up from the soil.

Practice crop rotation

This works as both an initial preventative technique and to prevent re-establishment of root maggots in future seasons. Rotate susceptible crops so that they don’t sit in the same bed more often than every three years.

How to control root maggots

If you already have root maggots, all is not lost—although the pesticide-based control methods are admittedly more effective than the organic ones. If you want to try organic first, though, there are a few ways to go about it.

Organic methods

1. Make your garden a home for maggots’ natural enemies: Many people have natural wasp populations on their land, but parasitic wasps can also be purchased. They are one of maggots’ natural predators.

Nematodes are also an effective maggot control method in many areas and can be purchased for home use.

2. If your plants will tolerate it, dig up the plants and wash the maggots off of their roots. Retrieve any stray ones you find from the surrounding soil and destroy the maggots, then return your plants to the garden.

Inorganic methods

The sole “conventional”, or inorganic, way to control a cabbage root maggot population is through pesticides. These are more effective than the organic methods by far. Because root maggots live primarily under the soil, most pesticides will need to be spread with a thorough watering to help the pesticides soak in.