Borlotti bean leaves not well

Hi, sorry about previous photo without any info, need to concentrate on what I am doing,  we grew Borlotti last year, pleased with our first attempt but this year quite a few of the leaves seem to be infected, this happens at different heights and they eventually turn yellow, dry up and fall off, we have planted about 12 plants against the fence at the bottom of the garden but not all plants have been affected, plenty of beans coming along nicely but feel we should have a bigger crop,  any help would be greatly appreciated