[Rizo]

Litteraly overnight they have be "munched" 

My thoughts are fly or caterpillas but approx 15 plants all leaf less 

oh well, got some back up ones in pots anyway but what can i do?

also is anyone else struggling with black fly on there runner beans this year?

TIA
Jon

[fatcat1955]

Are they covered, could be rabbits if it was at night, yes my beans are covered in blackfly but they are getting the soapy water treatment tomorrow.

[mumofstig]

If it was literally overnight, then I would think pigeons, rather than caterpillars? Can you see any caterpillars on the plants?

IMO It's best to protect any brassicas with fine net anyway.

And yes, there have been posts about blackfly on runners this year, so seems a common problem.                                                                                                                                                                                                                                                                                                                                                                  

[Rizo]

i found one or 2 but i just cant fatham out how so many leaves have been chomped overnight... all thats left is the stems.

Looks like i will be digging them up this weekend and replanting my back ups 

[Ice]

Blackfly have been a pest this year and my runners, amongst others veg were affected.  I find a spray of Provado24h does the trick.  Ok it's not organic but it is extremely effective, works for weeks and I only use it on things that won't crop for a fortnight at least. 

[JayG]

The longer you allow the blackfly colony to establish, the harder it will be to get rid of them.

It's a bit weird how they colonise runner beans; I've had them smothering single plants but none at all on adjacent ones!

Probably starting to sound like a stuck record by now but a tsp of washing up liquid in a litre of water in a sprayer works if you get to them before they really get a grip!