Q.I Have A Musa Banana Tree
The front of my leaves are very green and beautiful but I noticed underneath the leaves are a light brown and I don’t know what could be the problem I only fertilize it once every 2 months and I make sure not to over water it can you help me
Certified GKH Gardening Expert
I can't tell from this photos whether that is webbing or fungus, though, spider mites can lead to infection just as well. Fungicides can help, but you may want to apply a miticide just in case.
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/using-miticide-on-plants.htm