Cabbage root fly - oh no!!!!

[Catherine]

Went to our plot this afternoon and was really shocked to see two of our cabbage transplants have wilted. They were ok yesterday when we were there. We dug them up and they were full little maggots. We put collars round but these went in later than the first lot we put in and were just put in to fill a few spaces. They all had collars on when they were planted into the ground. But maybe they got it before they went into the ground. Will it affect the rest of the crop because they are looking really lovely now. Should I start with sowing some more seeds.

[Gracie]

Dear Catharine, I too went to inspect my brassicas yesterday and discovered alovely cauliflower all wilty!I had put large carpet squares around mine and still the nasty bugs lay their eggs. I have noticed that certain varietys seem to be more affected, this was a romanescu type cauli but so far no broccoli or sprouts have been affected and i have six rows altogether, last year was the same so this may be my last time with that variety. On most of the plants I did put two squares of carpet which overlapped and so far they seem to be ok. the one that was affected only had one square! If you wanted to re-sow you could try curly kale I've never lost a kale plant to cabbage root fly yet. If you do replant the poorly plant I always give them a good dose of seaweed solution.
All the best Gracie.

[Catherine]

Thanks Gracie. Today we lost three more cabbages to cabbage root fly. They were all small transplants that we used to fill gaps. We bought collars from LBS supposedly for cabbage root fly. But they were very hard and when we put them on the slit did not come together. In future we will use a better quality collar.

We have planted curly kale today.

I hope that the romanescu dont get it as these are our favourite.

[Johnboy]

Hi Catherine and Gracie,
I think that Catherine's statement 'perhaps they got them before they were planted' could turn out to be very true. Cabbage Root Fly will lay their eggs when plants are very young and I have found this to my detriment in the distant past. For that reason my Brassicas are protected from the day the seed is sown. Enviromesh covers will effectively reduce the incident whilst they are seedlings and when planting out I feel that it is best to use the bought brassica collars rather than home made ones. If in doubt try a very light dusting of Derris Powder (if you can get it) at the base of the plant before you fit the collar. I use Anti White Fly Netting to protect my bassicas but Enviromesh is particularly good for the purpose. I have heard of cases where Flea Beetle has got through Enviromesh but not sure if they were actually born in the enclosure after the net was placed and couldn't get out!
Once attacked and the plants have wilted they are of no use and you should dig them out taking a goodly trowel full of soil with the plant place them onto some polythene then go through the soil to remove and destroy all the grubs that will be about. Again dust the area lightly with Derris Powder. Allow that removed soil to completely dry out then go through it again before replacing it on the patch.
JB.

[Catherine]

Thanks John Boy We dug them out last night and got rid of them but it is so disheartening when you go to all the trouble of planting seeds, transplanting and then this happens. I did look at Enviromesh but for the size of bed that we needed it worked out very expensive. I must admit that I did not protect my plants before Iput them in the beds I have learned a lesson and next year will do things differently. I started them off in the polytunnel how can I protect the plants in there when they are small seedlings in trays. Do they crawl through the soil or do you think that the bigger plants will be safe? Also I purchased some collars but they did not fit properly round the neck of the bigger plants.