Did I ask a stupid question? I have looked all over the internet for an answer and I can't find anything that describes what I see in the photo...
I'd like to know what it is too, out of curiosity. Perhaps a detailed description of it would help. e.g. Does it scrape off? Is it raised or depressed? Did it appear suddenly or after an event?
Well I think I've uncovered the culpret... Wasp Killer. JoeReal on the other forum got me pointed in the right direction which got me to remembering when I sprayed a Wasp nest that was in the frame of my patio door... I think some of the spray found it's way to a few leaves on my potted navel. It sure had me spooked as I looked for hours on the internet and couldn't find anything like what I see on my tree. I thought it was a fungus of some kind.
