[scabs]

I noticed blackfly on my crop a few weeks back and used a speay to try to clear them - it seemed to work. In the past week, they are back with a vengeance and the plants are suffering (distorted leaves and fairly poor-looking pods...

I am loathe to respray now there are beans... Unfortunately, I can't remember the name of the spray. 

Any advice?

[Lardman]

You're fighting a loosing battle but take the tips out and apply thumb and forefinger to swash the little darlings.

You'll need to do it regularly though but you may keep them below the level that causes the plant harm.

I spray with bayers greenfly killer - keeps them off for a week but then they're back.

[scabs]

Cheers Lardman, I thought as much. I don't think I have enough thumb and forefingers, the whole crop is black with the little so-and-sos... do you spray while cropping then?

[Lardman]

I figure it can't be anywhere near as bad as the spray they use commercially.

I only spray when it gets really bad, they're sucking the life out of the pods and not just the plants here. The packet says no more than 3 spraying per season if I remember rightly.

If you're worried you can try using soapy water but Ive never had any luck at all with that.

[andy135]

I spray them with dilute washing up liquid. It takes 3 or 4 applications to dislodge them.

[domw001]

I have the same problem, but C'est la vie, we all have to eat.

The little tinkers have decimated half of my BB plants and last night i cut the badly infected ones down.

I had always planned to dig in the finished plants for green manure, so does any one know if doing this still ok with the blackfly affected ones?

[JayG]

Blackfly only colonise and breed on living plant tissue so dig away (might like to run them over with a lawn roller first if that makes you feel better!) 

(I'm a definite convert to the dilute washing-up liquid treatement by the way, although I don't think everyone feels the same; it does usually need to be done more than once though.)

[doubledug]

you can buy organic washing up liquid if that helps

[domw001]

Yeah I tried the washing up liquid thing, but the general consensus is you have to keep doing it for a few days for it to be effective and I just didn't get the time.

Now the runners are getting bigger I might try again.

[Salmo]

If you use a spray read the label. It will tell you the harvest interval that is needed between spraying and harvesting. For instance pyrethrins such as Bug Clear only need 1 day. Whether you wish to spay one day and eat the next is your choice.

Dilute washing up liquid is good but thorough coverage is essential. Forceful spraying with a hose is also effective

[noshed]

I think the autumn sown ones do seem to be able to cope better. Mine are all over now but the spring sown ones were a write-off.

[Weeble]

Mine also started off with just a few of the little blighters just before I pinched out the growing tips.

This was followed with an all out attack from them, which I initially combated with a commercial organic spray to no avail.

After chatting with one of the other plotters, I borrowed some of his extreamly strong (like treacle) nettle tea. This was diluted just enough to get it through the pressure sprayer.

Plotter 1, Blackfly 0.

[davmabz]

hi I dusted the tops of mine with ant powder a month or so ago, and their clean as a whistle!! not a sign of blackfly.

[Yorkie]

I very much doubt that ant powder is recommended for use ON edible crops, is it?

I certainly wouldn't want to eat anything after it had been exposed to that chemical cocktail.  Might get rid of the blackfly but poison yourself into the bargain 

[Starling]

No help for this year I know, but I have put nasturtiums next to mine and these are covered but the beans are black fly free.  Maybe worth a try next year