This is the first problem - Blackfly.
Although Blackfly do infest other types of bean, their favourite is the Broad Bean. They cluster on the stems, particularly at the growing-tip of the plant where it is softest, and suck the sap. To be honest, the damage they cause is rarely very serious, but it's certainly unsightly, and in severe cases may stunt the growth of the plant. The time-honoured solution to this problem is to pinch-out the tips of the plants once the flowers begin to fall and pods begin to set. After this time the plant is unlikely to get much taller even if not pinched-out. Personally, I'm not convinced that pinching-out makes much difference. In my experience the Blackfly just migrate lower down the plant. A more effective solution (if it's practical) is to wash the insects off the plants with a hose set to fine spray. If you're not bothered about being organic, there are many chemical sprays available that will kill Blackfly.
Here's another problem. Maggots that eat the roots of the plants. These are the larvae of various types of fly. The visible effect of these is a plant whose leaves droop and which grows very slowly - if at all - like the one nearest the camera in the photo below.
By the time it reaches this state it may be too late to save the plant, but it's not necessarily doomed. I used these nematodes to counter-attack the maggots.
Nematodes are like very tiny worms. They attack and kill the maggots which would otherwise destroy your plants. Of course, they are best applied proactively, before the maggots attack your plants. This may be an expensive solution though. The suppliers recommend treating your growing area at intervals of 2 weeks throughout the growing season. Each pack treats 60 square metres and costs approximately £6.50. My garden is so small that one pack is enough for all of it.
This is another problem that I have been facing recently - weedkiller contamination:
Beans are amongst the plant types most badly affected by the aminopyralid weedkillers used in agriculture and animal husbandry, as well as the clopyralid types often used in domestic lawn-care products. Despite allegedly stringent controls, these extremely powerful and long-lasting chemicals regrettably find their way very easily into commercial compost. Affected plants become distorted, thin and stunted, and produce little or no useable yield. This spoon-shaped leaf is a very characteristic symptom.
Last year my garden was very badly affected by weedkiller contamination, and I think that this year's symptoms may perhaps be caused by residues from last year. Certainly they are not so severe. My beans look as if they will be OK.
This is a Broad Bean plant affected by the weedkiller. The leaves are very thin and "fern-like". They have also rolled inwards on themselves.
For comparison, this is a plant of the same variety, showing normal leaf structure.
Unfortunately it is very difficult for the consumer to detect (or avoid) weedkiller contamination in the commercial compost sold in our Garden Centres. Big compost suppliers make huge quantities of the stuff and whether you get a good bag or a bad bag is very much a matter of luck. The only way to be sure you are not affected is to make your own compost! Since these chemicals are so powerful I would have thought it would be reasonable for the suppliers to be obliged to carry out tests to ensure their products are not contaminated, but that's not the way it works. The big multi-national corporations seem to be able to get away with anything they like, whereas we poor consumers seem to have no rights at all!
[If you are interested in this particular subject, please visit Sue Garrett's blog "Our Plot At Green Lane Allottments". Sue has accumulated a wealth of evidence and information about the issue.]