[Bricktop]

Last year my Runner Beans were smothered in Blackfly. Would planting French Marigolds next to them this year deter the Blackfly ?.

[Yorkie]

Welcome to the forums 

I think you are likely to have limited success with the companion planting method  , although it would look pretty 

[JayG]

As far as it's possible to tell, French Marigolds do seem to repel whitefly in my greenhouse - claims about their effectiveness outdoors on blackfly appear considerably more dubious...

No two years are the same - some years I have virtually no blackfly on my runners, last year they were smothered. Spraying with very dilute washing up liquid does work, although you may well have to spray more than once, especially if, like me, you fail to spot them before the colonies have really established themselves.

[wolveryeti]

Summer savory is reputed to repel blackfly, but I'm unaware of any scientific trials that can establish this at a level of confidence greater than hearsay...

[JoyPegs]

I also had this problem last year & the ususl washing up liquid treatment didn't help either.  I have read that a weak (1:10) solution of 3% H.Peroxide & water works - anyone tried that?

[jambop]

Last year my Runner Beans were smothered in Blackfly. Would planting French Marigolds next to them this year deter the Blackfly ?.

I have been told that the reasoning behind growing F. Marigolds next to tomatoes is to attract insects that like to eat green fly rather than a repulsive effect. My broad beans have been badly effected with black fly despite treatment with insecticide several times.

[Yorkie]

I also had this problem last year & the ususl washing up liquid treatment didn't help either.  I have read that a weak (1:10) solution of 3% H.Peroxide & water works - anyone tried that?

I had not heard that before.  It's not licensed as a pesticide and as such we can't endorse its use on the forum.  Also, I wouldn't want to risk getting the proportions wrong and overdosing it.

[Aidy]

In a pan boil up a litre of water, add a couple of orange peels, 2 garilc cloves crushed, a  chopped chilli and simmer for half hour. strain into a bottle.
In a sprayer add 250 ml of mixture to 750ml water and spray your beans.
I use this on Broad beans, brassicas etx and it keeps the black fly, white fly and even slugs/ snails at bay. Just spray every couple of weeks.

[Subversive_plot]

In a pan boil up a litre of water, add a couple of orange peels, 2 garilc cloves crushed, a  chopped chilli and simmer for half hour. strain into a bottle.
In a sprayer add 250 ml of mixture to 750ml water and spray your beans.
I use this on Broad beans, brassicas etx and it keeps the black fly, white fly and even slugs/ snails at bay. Just spray every couple of weeks.

Aidy, does that mix work on squash vine borers? (I'm hoping you all on the other side of the pond don't get squash vine borers!)

[mumofstig]

does that mix work on squash vine borers? (I'm hoping you all on the other side of the pond don't get squash vine borers!)

We don't get those, it's mainly slugs and snails that attack everything - not just the squash 

[Subversive_plot]

We don't get those, it's mainly slugs and snails that attack everything - not just the squash 

Still, might be worth a try.

Be glad you don't have squash vine borers! I try to keep them at bay with Bacillus thuringiensis (BT), but if that washes off, the borers get in the vines and kill the plant. Tromboncino and butternut seem immune though.

[al78]

I've had some success with running my fingers along stems covered in blackfly. I also noticed last year that for French climbing beans at least, the purple ones were far less infested than the green ones.

[Gleavo]

As long as the bean growth isn't affected I tolerate them as an inevitability on runners/broads etc and a great food source for beloved ladybirds. :-)