[daigo75]

Hi,
Yesterday I started spreading my radish a little, since some plants were growing in "families". Everything was fine, except for a single group of plants, which had a lot of tiny white maggots on the roots. I brought them inside and had a look under light, then did some research, and it seems they are cabbage root maggots.

So far I found only one plant attacked by them, but I can't exclude there are more. Unfortunately, I cannot take them out one by one, so I'd like to ask you if there's something I can do to exterminate these maggots.
A good half of the plants I have to put in the bed are cabbages or broccoli, and I can't wait the recommended 3 years before planting them.

Also, I've read that a fleece or net could help by keeping further flies away, but I don't know where to find one which won't cost me a fortune. Any suggestion is very welcome. Thanks.

[Liparis]

Hi Daigo75, Two methods, you can use Dursban to treat or when you plant your other brassica plants make collars for them. You can use cardboard, which might deteriorate quickly in wet weather or use felt. The collars prevent the fly from laying eggs at the base of the plant. I think you can buy pre-made collars.
There are two generations of Cabbage Root fly, the first over winters in the soil, these are the most destructive and attack seedlings as the grow. Your only course of action would be chemical attack as the eggs and larvae are already there. The second generation attack around June or July, I think, so preventative measures like collars can be used then. Put the collars in place at the same time as planting out your brassica plants. On ocassions a third generation can attack later in the year, they destroy your cabbage heads and buttons on your sprouts, the best course of action with those is to be dilligent with generation 1 and 2.
Bill.

[michael brenock]

good suggestion about collars to prevent cabbage root fly. Dursban is a very dangerous substance and should not be used. cabbage root fly does not attack the buttons of sprouts, this is caused by a different pest and requires different action.
michael brenock horticultural advisor(retired)

[Liparis]

There was me thinking all those years as a hands-on gardener was wasted and before becoming a head gardener, all those other head gardeners had taught me a load of old rubbish. I thought I better check it out. While there may well be another insect causes dammage to Brussel Buttons, Cabbage root fly does in fact cause serious dammage to Brussel buttons http://books.google.ie/books?id=3-w8AAAAIAAJ&pg=PA75&lpg=PA75&dq=Insect+damage+to+Brussel+buttons&source=bl&ots=9YU3ZkK_DV&sig=CIUXQJz6i7aRHry-Gc1X9f20Sx8&hl=en&ei=ocnnSZX1PIPI-Aaq7v3mBQ&sa=X&oi=book_result&ct=result&resnum=5#PPA75,M1

Or: Quote: "Occasionally, larvae tunnel into buttons of early-maturing cultivars of Brussels sprouts, leading to crop rejection by processors".
From: http://archives.eppo.org/EPPOStandards/PP2_GPP/pp2-07-e.doc

Even a numpty like me who is really incapable of googling properly can find such information, but googling aside, when teaching about Cabbage Root fly, it's very important to give the complete facts and not just part. First generation attack is the worst, second is pretty bad and third isn't too bad at all but it exists. Harvest your sprouts with a Cabbage Root Fly in them and your as well putting them on the fire than boiling/steaming them.

I'm not going to get into why or if Dursban is a dangerous substance, perhaps it's not even available to the hobbyist which means it should be sold through a poisons register, but I doubt that's the case for a chemical to be used on a food crop. Your other options of course would be lindane in crystal form or Malathion as a spray, both of which I've found to be inefective. Alternatively, forget planting out or sowing any brassica leaf or root plants until late May and deal with the second generation with collars. You will still have to find a suitable precaution for the third generation. Don't battle first and second then be mislead into thinking third doesn't exists or do what it does.
Bill.
Hands-on Horticulturist (retired)

[rosiemoo]

I am hoping there is an answer to root maggot and how to get rid of the little buggers! A few days ago a friend was burning all his brassicas because he had an infestation of root maggot. I came home and looked at healthy plants and breathed a sigh of relief. Not to be! This morning one of the lacinto kale plants was turning yellow and falling over. I picked it and of course, two small root maggots on the root!

Now what? Is there a nematode that could eat these things? Or is my only hope burning the entire crop of brasicas?

I am bereft.

Thanks for any input.

[michael brenock]

prevention is the only answer using either those collars referred to or keep the plants covered with fleece to keep out the fly.
michael brenock horticultural advisor (retired)