Oh wow spamming

Not sure what Mike is referring to.

Irostome, what is your general location? Do you know where the Yucca was grown?

The spots look exactly like what is called Yucca Leaf Spot, one of the common fungal disorders caused by a couple of different fungus organisms. Please put away your magic potion and research a proper fungicide, a real one.

Does this plant live inside? Let me know and I'll find some possible fungicides for you.

Thanks so much for the information Rhizo. I live in New England and got this plant maybe three years ago at a local Home Depot, but don’t know the actual origins. I left it outside each summer and it’s done well except for this summer. The rest of the year it is an indoor plant. Do I need to cut off the leaves that are affected? Should I change out the soil?

I daresay your problem starts at the roots - is it possible to show us a picture of the depotted rootball?

Cutting the leaves off might be counterproductive at this point, and I'd guess your problem is manifesting itself in the leaves, but it's not the leaves that are the problem.

Don't mind Mike, he's our resident Queenslander.