[lacewing]

My runner beans have a very bad attack of blackfly, the underside of the leaves are covered and the stems are loaded with this awful pest. I've tried hosing them off with a jet sprayer which does seem to clear them but they are back again in a few days. Any ideas as to what other method I could use before resorting to chemical spray.

[mumofstig]

Spray with water with a little washing up liquid in.

They are so bad this year that I think you will have to repeat every few days, whatever you do

[Sid]

Have found some blackfly clusters on runners also we tend to use a little soapy water as mumofstig said it seems to do the trick.

[greenhead]

I have been growing runners for years and never encountered Blackfly problems.  All my runner beans are affected this year yet the climbing French beans, just inches away, are not!!  even  the companion  Nasturtiums are not touched - what is going on this year?

[Frog]

My runners are covered in blackfly too - as is my rhubarb. There seem to be plenty of ladybirds around, but not enough to keep it in check. Think I'm going to try the washing up liquid trick. How strong do you make the solution though?

[BelgianPhil]

A bit of a follow-up question: i now have loads of blackfly on my nasturtiums (and only a couple on my beans), what do i do with the worst affected nasturtium leaves?
a) compost bin (dalek)
b) council green waste bag
c) general waste
d) leave them alone
e) none of the above

[greenun]

You are not allowed to mix harmless substances to spray on your plants as it is illegal under the pesticide act and can lead you to being barred from this site. Be warned..

[English]

My runner beans have a very bad attack of blackfly, the underside of the leaves are covered and the stems are loaded with this awful pest. I've tried hosing them off with a jet sprayer which does seem to clear them but they are back again in a few days. Any ideas as to what other method I could use before resorting to chemical spray.

I had a very bad case of black fly at the start of growth which completely ate away at all the young runner beans, they seem to have left now due to lots of heavy downfalls of rain and some, not many (plants) are slowly getting back to normal giving a small amount of produce.
new pots are nearly all gone (yum yum) and everything else is good, sweetcorn are looking good, can't wait til next month when hopefully they'll be ready. toms are to sat the least, great, just need a recipe for ketchup now as I've got 36 plants at my allotment.
Happy growing, don't let the nasty flys ruin your day.

[Fisherman]

This year for the first time I planted a couple of pots of nasturtiums up and put them at the side of the Broad Beans and Runner Beans. They apparently get attacked first by Blackfly which they did and at the first showing I removed the tops off the Broad Beens but obviously not the Runner Beans. The Broad Bean plants were virtually untouched and nothing at all on the Runner Beans but the Nasturtiums were decimated even after being sprayed with insecticide (used on the flowers but not the veg). Will do the same next year in the hope this wasn't just a one off and also look into more companion planting.

[slugwarrior]

after spending much time reading labels on so-called 'organic' insecticide sprays, i settled on the homebase own brand one.  it based on a soft soap rather than pyrethrin.  it has sorted out the green fly infestation under my insect netting!. It says that is is completely safe to use on edible crops. Personally, being suspicious of anything that comes in a bottle, i wouldn't use it on say lettuces but runner bean leaves, brussels tops and that would be fine.  if your beans have reached the top of the poles, you could just pinch the tops out  anyway which would reduce the new sappy bit the blackfly seem to find so tasty