My runner beans are going great guns; I can barely eat them fast enough.
But lately, the youngest, smallest beans seem to be going yellow and
flaccid. I think some of them are going brown and shrivelling up. It's
been raining quite a bit lately, but we've also had quite a few dry
days, so I don't reckon it's either drought or waterlogging. The leaves
seem fine and the plants are still growing and flowering. Can anyone
tell me what's wrong here?

Rhiannon