Root Maggots in Your Radishes and Cole Crops

At church this weekend a lady asked me if all radishes around here have worms in them. She said a friend of hers has grown them for years up by where I live and always has to soak them before adding them to a salad to avoid additional (unwanted) protein.

That’s certainly not very appetizing.

I think shes probably talking about root maggots. While the carrot rust fly will invade crops, and you may or may not realize it until you harvest, if the root maggot is a problem youll often have greater die off.

Controlling Root Maggots

Like the carrot rust fly, the root maggot fly looks like a tiny house fly, and lays its eggs in the soil near the preferred crop, which can be radishes, as well as cabbage, broccoli, rutabaga, turnips, kohlrabi and many other cool season crops. They tend to be more prevalent during the spring before the temperatures really heat up, so this is the time to nip their activity in the bud.

I know I sound like a broken record, but rotate your crops. This doesnt mean if you planted cabbage in a row one year, plant broccoli in it the next one. You need to think in terms of entire plant families. Its more like, if you planted a member of the brassica family (cabbage, broccoli, cauliflower, etc.) in the location last year, dont plant one in the same place this year. Plant squash or peppers there. That way the insects that are partial to one family wont have their favorite meal ready when they emerge.

And when youre dealing with a root maggot problem, you want to turn over the garden space a couple of weeks before planting. Since the pupa overwinter several inches deep in the soil, this can bring some of them to the surface before the conditions are optimum for them to survive. This can knock down the numbers from the beginning.

If youve had a lot of issues with root maggots, plant later in the season. Setting out cabbage and other cool season plants at the beginning of June is hard for those of us who like to gamble with Mother Nature and try to plant earlier every year, but if theres nothing to eat when the pupa emerge you wont have the adults laying eggs later, either.

When they emerge, they are tiny flies that will soon lay eggs at the base of the stems of their favorite plants. The maggots hatch in 3 to 7 days, and then head back in the soil to munch on the roots of the nearby crops. Cabbage and other plants will die when theyre roots are consumed, and radishes or other root crops just look nasty.

Another option to discourage infestation is to cover the vulnerable crops with a floating row cover. Like the carrot rust fly, be sure you have it pinned down securely so they cant sneak underneath. Or, you can place 4 to 5 inch squares of tar paper around each plant so the fly cant lay the eggs near the base of the plant. Diatomaceous earth, wood ash and red pepper can also be sprinkled around the plants to dissuade them.

Meet Amy Grisak

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