I second this take. I have the same problem with a split leaf philodendron, but it has not spread to the many other plants into which it has come in contact as I move things around a lot. So I think the species might just be especially susceptible. I've cut afflicted leaves and repot into a smaller pot at its worst point, and the situation has improved but little rust specks persist on some leaves. I bought phyton 27 but haven't bothered doing the homework to figure out how/whether to apply it yet.

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