Hi to you both. Sorry for the delay. Because of the poisonous aspect of rhubarb leaves, some will advocate against it but all I do is boil some leaves, strain off the liquid, once cool it can be used in a normal household (cleaning fluid) spray to deal with aphids. I've got a 1 litre container in the shed ready for 2023. Those who don't like the idea will prefer not to mix it with food crops for fear of cross infection, but I'm happy to do so as infected pods/flowers are a long way from the edible beans which, after all, are thoroughly washed AND boiled before being eaten.
Thank you - looks like something I'll try - I guess you mean contamination?