I have a huge 3′ round hanging Stag and need to know how do I stop the brown fungus.

Question

It is slowly moving up the back of almost all the fronds.

 

Answer 1

Would you be able to send a picture? I am not quite certain it is a fungus.

But, until you can send a picture and we can positively identify it, it would be a good idea to treat the plant with a fungicide. If it is a fungus, it will help stop it. And if it is not, the fungicide will not hurt the plant.