Black pimples on broad beans

[Monika]

I have just harvested the last broad beans and a few of the bean pods had hard black pimples on them, the beans inside were fine. What are these, I wonder?

[oldherbaceous]

Dear Monika, i meant to try and find out a little more about this, as i don't know the answer. But i'm sure it is the same problem that i have on some of my Runner Beans. I have a feeling it could be a little midge type fly, that sucks the sap from the bean leaving a clear pimple, which turns to black on Broad beans.

I could be wrong, but it could get some other ideas going.

[Monika]

That sounds interesting, OH. I have never seen these 'pimples' before. They are black, quite small and hard and raised but, as I said in my original post, the beans in the pod were fine. And it only affected very few pods.

[John P]

Monica & OH,I have had the same problem with these raised black pimples on Broad Beans over the last few years,but this year,Ihave found that quite a few of the pods have been penetrated by some sort of bug. It leaves some of the beans with black marks on them.as though they had been eaten. My theory is that as I have had a bigger infestation of Black Fly this year then the usual and also earlier, that like Pea Moth the Black Fly has managed to get to the beans as they were developing through the flowers. I have delved books and the internet for pests and diseases on beans and have come up short. It would be interesting and helpful to hear other peoples views on this problem. JP.

[oldherbaceous]

Morning John P, that's an interseting line of thought. i'm sure what ever is doing it, is causing the same problem on my runner beans as well.

I think the coulour black, from the pimpels on the broad beans, is caused by the dye in the pods, because i have noticed they start off clear at first, the same as the runner bean pimpels stay.

[FelixLeiter]

Black pimples are the scars from damage caused when the pod was first developing, or even while it was still an ovary. Microscopic piercings caused by aphids or other insects with piercing mouthparts expand into larger marks as the pod develops.

[oldherbaceous]

Thank you Felix, we were sort of, all right!

[Monika]

Thanks, Felix - it's good to have you on the Forum!