Fungus on my lemon tree.

I have recently planted a lemon tree from seed and am growing it on my windowsill- just from a regular supermarket lemon. It is now about a foot high, but seems to have developed some kind of fungus on the stem. The fungus is in small, thin, semi-circular hard plates, is light brown/beige and some has what looks like hardened drops of amber coloured liquid on the ends of the plates. I have so far just been scraping it off, as I don't know whether to use a fungicide or if there is a less violent method of getting rid of it (or even if it is necessary to get rid of it- so far it does not actually seem to be harming the plant). Please advise what I should do?

 

Do they look something like this? Scale via the University of California Integrated Pest Mgmt program (click on the links to see photographs) Note: this is an insect, not a fungus

 

I thought seeds from supermarket lemons would not produce fruit bearing plants. Can anyone else confirm/deny?

 

No, the plates are not flush with the stem, but perpendicular to it. And they grow like a fan opens. This is Northern England by the way if that helps?

 

Post a photograph (or scan), if possible?