The circular nature of the spots leads me to suspect a fungus. The fact that you do so many things to keep a humid environment (not needed by citrus, which grow so very well in desert-like climates), further leads me to fungus.

Try dropping the misting and the humidity tray; and give it a shot of some sort of fungicide; you may see your problem go away.

Thanks, John. Do you have Meyer Lemons? Which fungicide would you recommend?

I gave it more humidity because it was not showing any new growth. Once I upped the humidity, it immediately threw new leaves and now buds. Could be just a coincidence but I thought you would appreciate all of the facts.

Thanks,

Terri

Terri,

Yes, I have some Meyer lemons; and I treat them twice per year with a systemic fungicide, Bayer Silvacur. I don't know if you can get that product, but look for a fungicide by Bayer for home growers. All citrus tend to grow in spurts; so it was unlikely your addition of humidity was the cause of new growth. A good citrus fertilizer applied regularly is all you need; for Meyers the ideal fertilizer will have an NPK ratio of 3-1-2 with Calcium, Magnesium, Zinc, and Iron.

johnmerr, I am going to try Citrus Foliar Spray first since no one seems to be recommending which fungicide available for home use. The few I looked at were scary. I do have immunox and several others I use for my orchard and shrubs but I prefer to treat for a specific problem. What kind of fungus does this look like to you?

Thanks, Terri

I would not even worry about the nutrients of your tree using Foliage Pro , one that provides everything your trees needs in a perfect ratio including micro and macro nutrients and all the nutrients that John spoke of......

Why are you misting the leaves though? Do you have fan set up? How close are the lights to your tree? When did those spots show up? Right after you bought it? Do you summer it outside?

Mikerno, The yellow spots started right after I received it. I have only had it about 6 weeks. I mist most of my indoor plants except succulents and desert roses. The summer was over here by the time I bought it. Yes there is a fan. I have my orchids in the same room.

Barb, I will try the immunox. Will I lose the buds?

Hard to tell. Fungicides don't cause bud drop. But young citrus under stress sometimes do drop buds. Don't worry if it does as it's too young to support fruit anyway without causing a little more stress and it will make more soon enough if its happy. I'd enjoy the flowers if it keeps them and take off any fruit this year. Flowers don't stress it much. Concentrate on growing the tree strong this year so it can give you lots of fruit in the future. Read the threads here about proper soil, watering, etc and you'll be fine. Lot of good info to be found on past threads.

Terri,

Where do you live?

And where did your tree come from?

Although johmerr is far beyond me in knowledge about citrus, I have doubts about saying this is fungus.

On a site describing diseases in United States, I found this about citrus leprosis :

http://itp.lucidcentral.org/id/citrus/diseases/key/Diseases_of_Citrus/Media/Html/Leprosis.htm

Leaf pictures are about half way down the page.