Fungus on heritage variety bean plants

(Question)

I have grown beans before without problems, but this year I planted a heritage variety of pole bean seed from Spain and all the leaves have some kind of fungus or something leaving reddish yellow spots all over them. What can I do?

(Answer)

It sounds as if your bean plants are infected with rust, which was a common problem in beans before newer varieties were bred to be resistant. The common bean rust is common in areas with high humidity as is the case in Toronto. Although it is possible to employ fungicides, they are best used very early in the infection. It is likely that your plants are too far gone to manage the disease although you could try a fungicide to try to safe some of the crop. Unfortunately, many older varieties of plants are more susceptible to disease than newer ones.