[1st time veg grower]

Having a nightmare with my brassicas. A couple were looking a bit dodgy yesterday and then we've had strong winds all day and some of my brassicas had keeled right over. To begin with just thought it was the wind but then had a look in my veg book and the description matched a couple of the descriptions for bugs in the soil, so I dug up an affected plant and discovered it had no roots!!! I then had a furtle and discovered the bug below.

I snapped the stem of the affected plant to see if it was 'tunnelled' but it wasn't you can just make out the bug on the left:


Close up pics of the bug:



I am gutted this is one of the smaller plants. I read the remedy -burning the infested plants- which means I would lose all my larger plants too.

So is it what I think it is or not? If it is, is it possible to grow brassicas in pots? I have several more to go out but you can't grow them on the same plot if it is. I grew brassicas on the bed next door last year without any problems.

Any advice or help please?

[1st time veg grower]

Oh, and is it possible to grow anything in that bed at all instead of brassicas?

[1st time veg grower]

Have done an internet search of photos and think its actually the dreaded larvae of the cabbage root fly. Equally as bad and now really annoyed with myself for not buying the collars that I almost got or covering my crops with environmesh.

Same question applies though... any help?

[Ice]

I've just looked in my Doc Hessayon and they do seem the likely cause.  He says to apply a nematode  based insecticide.  Chafer grubs are larger and there are no signs of tunneling for cabbage stem flea beetle.

[DavidT]

It`s cabbage root fly. Use collars in future. Unfortunately there is no decent soil pesticide anymore.

[1st time veg grower]

Have just ordered some nematodes online - says it can treat cabbage root fly too? So if I want to plant some more cabbages etc how long after the application of nematodes can I plant them? I understand that the nematodes have to be reapplied. My understanding is the fly can continue attacking over the course of the year so should I cover the bed with environmesh then or is there little point in trying again as the larvae are already present?

So so angry with myself - some of them were looking really good. 

[DavidT]

As I said, use collars. Much cheaper than nematodes and easier to use.

[1st time veg grower]

But if they are already in the soil, won't they just go to the new plants and scoff their roots instead? The collars will prevent a new attack from the flies laying the eggs but not the larvae that are already present in the soil surely?

[DavidT]

As far as I am aware they don`t migrate plant to plant.

[gem]

Hi sorry to hijack but i have the same problem a relative newbie and didnt know about collars and the like, I have uprooted all my plants washed the roots and picketd off all the maggots (chickens loved them!).

I know have them all groing in water in the utility till i work out whats best to do, i think i caught mine very early and most plants still have roots and are growing fine.  But like you i think putting them back with collars now will make no difference as the eggs already in soil??

So far they have attacked my broccoli, chinese cabbage, kale and pak choi (which is most of my crop!)

Any ideas?

[1st time veg grower]

Oh ok David, that's reasonably good news then.

Gem, Hijacking allowed!  I will be doing the same as you tomorrow - there are some healthy looking plants in the same bed so will dig them up remove the maggots (i squished the one in the pic out of frustration but feeding the chickens with them will cause just as much joy). Then what I will do is pot them into large pots with collars as there are still flies about that will want to lay their eggs even if they do survive this attack. Then seeing as I've already ordered it I will treat the bed with the nematodes just in case and then plant out my spare awaiting seedlings either with collars or under environmesh.

I love my brassicas, so waiting til next year is not an option.

[gem]

Yeh think i might order some of that stuff too, as im my research on the blighters some people say to leave the plot free of brassicas for 3 YEARS!  I only have two small plots so that would be me out of the game for 3 years :-(.  I was surprised they went for my pak choi I have checked my celariac and nothing yet and also my chard and nothing yet so they are keeping my plots from loking very bare at the moment!

I have bought collars and fly traps but I fear damage already done.  Lets hope we can salvage something.

Oh i did read in a book to use derris and that would help and i have read that some derris was banned but there are still some forms avalible so maybe someone can advise on that?

[mumofstig]

As you dig each plant try and remove any maggots that you see.

I would also make sure you use collars this year and not rely on the enviromesh alone.
The maggots in the ground may hatch into flies and then be trapped under your mesh with your new plants as a free dinner for their babies, and the cycle will start all over again.  

If you use collars, my reasoning is, that any flies that hatch will fly away as they will not be able to lay eggs successfully around your plants.
Hope you can save some

[1st time veg grower]

Thanks MOS, will do. I hope we can save some too. Just goes to show that just because you don't suffer with something one year doesn't mean you won't get it the next, and of course...prevention is always better than cure! Hindsight is such a wonderful thing!

I grow in my garden so not much space between my seperate beds, so I wouldn't be able to plant mine elsewhere. And I can't do without my cabbages for three years! Had planned to grow both winter and spring ones for next year too...

Gem, I just did a search and read that some people suggest 'earthing them up' - so replanting them as deep as possible, in order that they might perhaps grow new roots.

[Salmo]

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.