[gem]

Thanks for that info that helps a lot!  So now i have dug all my effected veg up and cleaned all the maggots off and been keeping an eye on them the last few days in the house, I should be able to re plant with collars that that should help. 

The plans are all well established but there was a lot of maggots on them even the pak choi (mainly inside the leaves on them).  What about the eggs still in the soil will this help with them too?

[PennyS]

Cabbage root flies lay their eggs on the soil close to the brassica plant stems. The tiny maggots crawl down into the soil out of the sun and chew away at the roots. The odd one or two per plant will not usually be harmfull. It is when there are a dozen or more chewing away that the plants begin to suffer.

The collars that have been talked about are very effective. You can buy them, but you can easily make them yourself from anything stiff and flexible such as cardboard, old pond liner, roofing felt. Cut out a disc about 6 inches in diameter. Cut a slot to the centre and if it is stiff material cut a gap in the centre to fit round the stem. Place a collar snug round each stem flat on the ground.

The flies will try to lay their egg near to the stem and will lay them on the collars instead. When the tiny maggot hatches it is unable to crawl into the earth and perishes in the sun on the collar. Perfect organic solution.

It helps if you allow your plants to get 6/8 leaves before planting out. The modern fashion seems to be planting out at only 3/4 leaves which means they are vunerable to not only cabbage root fly but also flea beetle.

After planting out the next thing to watch out for is grey apids in the growing middles of the plants and under the leaves. They are often difficult to spot and the first thing you notice is some plants not growing properly.

Thank you Salmo - and others - I have at this point not put any collars on.  I think I will be making some with the kids today though.  Cardboard probably, don't have any roofing felt to hand.

[1st time veg grower]

Ok so I have a triple whammy. It turned out only 3 of the plants (out of 20) had the cabbage root larvae (unless the others had done their deed and grown into the flies). A few of the others looked exactly like the picture for damage caused by chafer grubs and then the rest had grey grubs that had tunnelled the stems as in the description in my book of cabbage stem flea beetle, however they were more like 2 mm long and grey not cream grubs. Any idea what they are?

In short all plants were affected by something and are now chicken food!

Then to make matters worse I have back up plants in my coldframe and on inspecting them I am convinced some of them might have something wrong with them too.

Not sure what to do next - I could go out and buy some plug plants but I only have that space available for brassicas - will the nematodes kill all these pests or do I just give up on brassicas for this year?  

I edited this because at first I thought the grey grubs were the aphids Salmo was talking about but then re-read the post more carefully!

[gem]

Oh no thats no good.  Im afraid I cant help but Im sure someone else can.

I was at work on my patch today and found the maggots had eaten all my spring onions too!

But I have ordered the nematodes too and hope this will help along with the collars, digging them up and cleaning them!

[1st time veg grower]

Am much happier today! Went shopping and out for dinner and stopped thinking about it and today have decided to not let the little insects get to me and not to give up on my brassicas!

Thankfully the cabbages hadn't become chicken food yet and actually some of them were so large they were too good to be wasted on the chooks anyway. They hadn't wilted for lack of water (or soil) overnight either. So I did a little experiment. I took one of the ones that I thought had been tunnelled into and cut the stem and it hadn't been whatever the grey things were, they were eating them from the outside - no tunnels. I did the same with a 'dodgy' seedling and it was fine too, I think they are just starting to get leggy so will move them to a different spot until I think the bed is safe to plant them out. So seeing as the larger plants seem to want to live, I might give them a chance anyway and see how it goes. The trauma of transplanting them may be too much anyway...but nothing ventured!

The nematodes hopefully will deal with the plot plus the mesh and collars - so may be the winter and spring ones will have a chance along with my seedlings.