Gardenia Leaves Have Brown Encrustation On Larger Leaves At Base

Question

Black flies were attacking New growth. Plant are kept inside with high humidity.

Answer 1

You can remove the leaves if there aren't too many. It's likely a fungal disease.

https://hgic.clemson.edu/factsheet/gardenia-diseases-other-problems/

Answer 2

Hard to diagnose without more information and pictures. It may be a pest (scale, etc.). Review the information on this link and post again if necessary: https://www.gardeningknowhow.com/ornamental/flowers/gardenia/growing-gardenias-indoors.htm