It looked to me like Spider Mites damage, but I didn't notice the other signs. It's affecting 2 other bean plants I have but not any other variety of plant.

Anyone come across this type of disease in the past? Any advice on how to deal with it?

Thanks in advance for any insights or advice,
Dan

There's no real "knockdown" treatment, but copper fungicide can greatly slow the spread. Chlorothalonil (Daconil) will protect leaves that have yet to be infected. I don't like using copper regularly because of toxicity concerns.

As for organic treatments, Serenade is listed for bean rust as "suppresses" rather than "controls".. usually means it's best used as a preventative. Actinovate isn't labeled for it. Wettable sulfur is labeled, but has questionable efficacy.

Rosemary, thyme, and clove oil are also listed as OMRI options for bean rust, in the form of Sporan fungicide. Efficacy has been shown only in vitro.

Thanks for your advice,
Dan

You might want to use the finger method to continually observe the container wetness and notice the plants health at the same time. After doing this awhile you can usually tell just by looking at the plant the state of the soil wetness.

Also, even if my plants were fertilizer deprived, but the soil wetness was good, they didn't develop disease (they just stayed yellow in color and didn't grow much).

Also watering the leaves on a hot sunny day, helps prevent disease. Spore/fungus will start to grow but as the leaves dry in about 1/2 an hour, they die.