Outside plant (large)
I just noticed two leaves that have a large spot growing on them. The spots look more white than brown and it just started developing two days ago. Help Unable to send photo
Certified GKH Gardening Expert
A white powdery appearance on leaves is usually caused by powdery mildew fungus:
If the spots later turn brown, it is most likely something else. What it is would depend on what plant it's growing on and the particular appearance of the spots.