|All of my cinnamon ferns have something growing on the back of each leaf. The fungus, if that, is a series of small circles, each about the size of the head of a ball point pen. The circles forms in two or three rows of the back of a healthy leaf. It starts (the circles) out pale green and eventually turn brown. Each leaf as it is affected slowly shrinks and curls, like the life is being sucked out. The fungus starts at the tips of frond and spreads inward. No other plants in my otherwise healthy garden are affected. I have no other ferns. What is it and how do I get rid of it? It started last summer and came back this year.
|Based on your description, it sounds like the spots are actually the result of the ferns setting spores as part of their natural reproduction process. I think the browning and drying you described from the tip down are actually the the result of warmer and drier weather taking their toll. Ferns as a rule need a very moist soil (almost wet) and plenty of shade to hold up well through the hot summer season and as it happens, the two events tend to coincide.