Allotments 4 All

Hi everyone, in a small raised bed I have a mixture of things sown from seed. The bed had fresh compost put in before sowing & a net cover popped over straight after sowing. The dill & coriander are doing very well as are the Chinese cabbage but the Pak Choi & Mooli have been a disaster  ???
The pak choi started off very well but then stopped growing & leaves started to rot well before the plant matured. I have pulled them up today & can't see any pests either on the leaves or hidden in the roots. The mooli also started well & the foliage grew fantastically well. Today I pulled a few only to find virtually no growth of the actual root. The small radish that was there had brown tracks running through them like something had been burrowing into them but I couldn't find any critters in the soil.
The compost was a mix of Wilkinsons multi purpose & Miracle grow. I have another bed right next to it with the same compost mix where all plants are doing very well (this bed has Purple Osaka in it & a different variety of Pak Choi along with kale & celtuce).
Any ideas about what has gone wrong? Do you think it's the wet weather or a pest? Thanks xJane   

The brown marks on your mooli sounds like cabbage root fly dammage. Sometimes mooli will get this damage at soil level with the part above the soil and below perfectly usable.

But if they are affected early they won't have the strength to grow out of the fly's damage.

So it could be that your mooli and pak choi were affected early so they are stunted while the other brassicas you mentioned were able to grow stronger.

It also explains why the non-brassica crops you listed are growing well.

Thank you so much ed dibbles it now makes a some sense why some things have thrived  others failed  ;D
I have generally avoided growing most of the brassicas in the past due to the many pests they get but thought I would give most of them a try this year in raised beds at my back garden rather than the allotment - I was hoping many pests wouldn't find my veg as no other veg is grown any where nearby.

As the bed was netted from the moment seeds were sown could the cabbage root fly have been hiding in the fresh compost I used? Would it survive in plastic compost bags? Or is it tiny enough to get through standard netting?
Thanks xjane
 

Yes they are small enough not to be put of by standard netting. Environmesh or fleece are required to put a halt to their antics ;)

Thank you so much for your quick reply I really do appreciate it very much especially as I made up 2 more raised beds today for brassicas. I had planned to use net again but now the beds will definitely be covered with fleece the second I plant out anything! I'm off to google more info on these pesky things, hoping they aren't around all year???? xjane