For those of you who grow these, how do you deal with the dreaded Black Fly?
I worry about using chemicals on my food products.
Thanks. 
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I use a solution of diluted washing up liquid in a spray Mups - that seems to work for me.
Thanks Margaret.
Can you give me a rough idea of the dilution please?
I can give a very rough idea of the amount Mups, it’s a bit trial and error to start with. I put a squirt of liquid in the spray bottle and then fill with water and shake. The spray bottle is one of those you can buy to spray the roses. Sorry that doesn’t seem much help does it 
I didn’t get any blackfly this year… Mind you, I didn’t grow any runner beans either.
I used dilute washing up liquid last year but to very little avail and I lost the whole crop it was that bad, but this year I bought some Pravado bug spray that is safe to use on edible crops, although I haven’t needed to use it yet because I am inspecting the canes every day and taking off any infected side shoots. The prevalence of the black fly seems quite low this year, although they did damage to a blackcurrant bush earlier on due to my negligence in not checking for the little blighters.
I really am always loath to use insecticide of course for fear of killing pollinator insects, so it really is a final straw solution which hopefully won’t be needed anyway!
Another vote for washing up liquid. Seem to work
I have just spent half an hour swabbing black flies with kitchen roll soaked in water and washing up liquid. I like to squish the flies in the kitchen roll.
i also remove any surplus leaves that are covered in black flies…
Thanks everyone, it seems washing up liquid is the answer then - plus daily vigilance and not letting the little blighters get too bad in the first place.
Like others, I haven’t got a problem at the moment, but it is early days and I want to be prepared.
As I said earlier, I am loath to use chemicals on food products if avoidable, but also I my dogs poke about everywhere they shouldn’t! 
I have also heard about a bit of vinegar mixed in the soap & water helps too, don’t know if anyone has tried this?
Yes. When I had an allotment back in the 70s, one of the older gardeners told me to use used washing up water with a couple of teaspoons of vinegar mixed in. I still use that mix for greenfly on roses 
Aha. That’s interesting. Thank you Percy.
My Lupins attracted the black and green flies and have noticed here in France that most veggies beds have at least marigolds and other flowers cant name them as yet… sure they are used to decoy the little beasts away from the veggies…
I have always used a few drops of washing up liquid with water and spray them like most peoples answers before me…
We cannot grow Runner Beans at all here…
They look healthy Realspeed, but I asked how people keep the Blackfly away? Do you get that problem with yours?
I spritzed them away with a hose. Although I found that it was all to do with position. Avoid growing them near trees or other shrubs.
Having grown them a few times I’ve now realised nobody likes runner beans. Nobody wanted to eat them. I made a stew which included just the beans themselves last Summer. It was the neediest dish. You have to harvest so many beans just to get a bowlful.
So this year it’s tomatoes, potatoes, parsley, fennel, dill, mint and chard. There is also a large cucumber plant in a pot in the house with teeny tiny cucumbers starting to form. Not sure whether that will be a success yet.
Blackfly don’t seem to like tomatoes or geraniums. I wonder whether it’s worth planting runner beans surrounded by tomato plants to avoid some pests like blackfly.
Hi
Mine are a disaster this year, I am on my third planting.