Flowers dying off broad bean plants

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Q: The broad beans I planted to grow up the side of my shed seemed to be doing well and were producing lots of flowers. Then I noticed the bottom flowers were dying off (shrivelling and then turning black). I checked for insects and didn’t find any, but sprayed the leaves and stems with a soap solution, being careful to avoid any flowers, just in case. The flowers are still dying. I’m losing more and more up the plants. There is some ‘nibble’ damage along the edges of some leaves. The only insects I can see are quite a lot of small ants. They seem to be drinking from the flowers. Could they be killing them? If so, what can I do? If not, what else should I be looking for/doing? The beans share the shed with some pole peas that don’t seem to be affected by the same problem. There are winter lettuces, kale, one green bean plant and a few everbearing strawberries planted at the base of the beans and peas.

Ants in general do not chew on plants. They are just taking nectar from the flowers back to their colony.

Flowers dying or simply dropping off can be due to either temperature or soil moisture. Broad beans (Vicia faba) thrive in cool, moist conditions such as heavily manured soil that is well-drained. Best planted from Oct. to Nov. in milder areas or Feb. to May for other locales.

I do not believe temperature is an issue, either being too cool or too hot. We have not had any appreciative heat wave, e.g. over 30 C. But this has been a drier spring as our precipitation year to date (Vancouver Int. Airport) is below normal. Give plants a good soaking once or twice a week plus maintain a good layer of organic mulch to stabilize soil moisture.