About your only choice. Nothing on the market that you can buy without a license that will take care of those things. There have been some good results posted with entomopathogenic nematodes, especially Steinernema spp. But again long term project.

Yeah, thinking it's too late for that.

In my experience, the mama flies lay eggs on isolated plants, or sometimes two plants growing close together. I have more problems with cabbage root maggots in August than in spring, but even then the damage is light and spotty, or zero damage with row covers.

In the UK gardeners are having good luck with vertical enclosures made of window screens, with the tops left open, for deterring cabbage, onion and carrot root maggots. It seems that the adults strongly favor horizontal scouting for egg laying sites, which is impossible when the crop is surrounded by a screen enclosure.

Another one bit the dust today, a cabbage at some distance from the kale.

I'm growing more brassicas than usual this year, in rows next to each other. I may have attracted them with all the abundance.

Yes, once you start growing Brassicas those moths figure out what you are doing. I get plants looking normal one day, then the next they start to wilt. Look at the roots and the roots have been destroyed from the stem under the surface. Pull on the plants a little, near dead plants will pull up easily since the roots are going.

I've used BT in the fall with some success, but it seems too rainy in spring to help. I have not tried poisons or floated row covers. I only grow a few plants, not a big row. Almost a waste of time, even some of my Kohlrabi die even thou I hope they will mature quickly and avoid this problem.

I wonder if Spinosad ...

Spinosad is a bit more broad spectrum for my liking since I've read that the target pests come back even stronger because one kills off natural predators. Not sure if it controls root maggots. Pretty pricy too compared to BT..

Kevin

I bought some insect netting that looks like tulle. No root maggots so far.
I've heard that Spinosad does not significantly affect beneficials since it it needs to be ingested to be toxic, as opposed to being a contact poison like pyrethrin, and most beneficials are carnivores. Bees are an exception which is why you spray Spinosad after dusk.

Too late to net here. That will have to wait til the next crop.

ahh. It's a FLY. I don't see BT doing much good.

Kevin

Row covers will work IF the soil is not infected. Once the larva is in the soil, they will happily recycle under the row covers. They can reproduce 3-4 times in a growing season.

It's not the fly, it's the larva of the fly - maggots are fly larvae.

ltiton: lol. I'm aware what MAGGOTS are. I thought that root maggots might have been a misnomer though since somebody mentioned MOTHS and BT.

Sounds like nematodes are the only true long term method for success and HOPE is for the short term. I read that sticky traps are helpful though.

Kevin

Sigh... root maggots. I cannot grow a decent radish because of these things. I planted 7 cauliflowers this year and only two will make it to fruition. The others I noticed wilting on cool days when the sun came out. Tugging on these plants would pull them right out of the ground revealing brown, stubby roots. I may try the tulle approach.
Oddly enough, my collards and kale do not seem effected. and the brussels sprouts only mildly.
Another approach is to place plastic disks around the plant stem to prevent the fly/larvae from getting to the roots. Never tried it so I don't know if it works.

I had moderate success last year with a thorough soil drench of Neem. Didn't kill every maggot, but it knocked the population down enough so that most of my crops survived, and I had every single one in the bed infected before the drench.

The best way to deal with them is making the egg laying location at the stem as in hospitable as possible. Use cotton rounds and diatomaceous earth and organic insecticide and on occasion some still manage to scathe through. I don't know of a more formidable garden foe than cabbage root maggots. I'd rather deal with tomato blight or cutworms