Last year,my first year on an allotment, I had disastrous
results with Brussels sprouts.
They all opened up like flowers and I was told that I had not
transplanted them deep enough and not firmed them into the
ground enough.
OK, so I have followed advice and hopefully this will make things
right for this years crop.

Thinking back, the other problem I had was white fly, I had loads
of them, I sprayed with soapy water but it didn't seem to get rid
of them.
I don't know what harm they do, if any, but in any case I would
like to be free of them so now the question.

How do I prevent them in the first place and if I can't prevent them
coming, how do I get rid of them.??

Advice would be appreciated.

Wally