I’ve got a strange fern inquiry! Attached is a picture of a client’s Ostrich fern with strange, beige window-like spots. They don’t seem to have anything inside the windows (thinking there might be a new leafminer out there I inspected them with a 10x magnifier) Is there a fungal problem that I haven’t heard of that attacks fern? I thank you very much for your consideration!
While Ostrich ferns have no particular insect or disease problems they are prone to leaf scorch and need constant moisture to avoid this problem. It is common to see the fronds depreciate as the summer progresses. I think this is the issue with your client’s fern. Check to see if the growing conditions for the fern have changed. Is it receiving more sun than in the past? It can tolerant some sun as long as its kept constantly moist. Sometimes a new flush of growth appears in the fall. The link below has some good information about Ostrich ferns