If using a good fertiliser with all the minors, you shouldnt get a deficiancy, if there is one , the 1st to go for is adding sulphur to the pots, it alters the pH , incorrect pH will give signs of a defficancy.

If you have a tree with a defficiancy, if you spray every night with the normal fertiliser containing the trace elements it normaly corrects itself, spraying the element (apart from iron) seems to work quicker

Most fertilisation problmes look diffrent so you can see which is which, if i guess what it is up, i add extra element to the spray for a few days, or just do an extra spray with just the element needed, both seem to work the same

If it looks like a deficiancy and doesnt correct itself with a program of fertiliser spraying every night, i then add sulphur to the pots to correct pH slowly and keep spraying

adding random extras such as iron sulphate or magnesium or vinegar i just chuck a small amount in the fertiliser bucket evey few months , just incase

mike, I thought that you were using a product with the minor elements in it. Truly, if you are using a decent all purpose fertilizer, and adding a dose of miner (trace) elements occasionally, you should not ever have to worry about adding vinegar, sulphur, or other products that could totally screw up your pH.

Would you like to know how many times in twenty or thirty years I've had to deal with nutrient deficiencies in my container plants? Never.

Hi rhizo,
This you are right. I just wanted to be on the safe side incase my fertilizer does not work for all. In fact, what's weird is that I feed all my plants the same fertilzer that a member here made me with everything neccassary in it.. I think I butchered the word!lol Anyways, and it seems that a couple of trees here and there will still get faded leaves to yellow. Especially a couple in the smaller pots.
I have a small ponderosa lemon all of a sudden with lower leaves turning yellow, the older leaves,the two nearest to soil at the base of trunk, and who knows why, even though I feed them all the same stuff.But this plant is still green the rest of the way up. All my others are so green and healthy. Maybe it could be anything. Even a change in window sill temp.
But my idea was to douse it with a made up gallon of all these things together to see if anything in this mix as a test subject for that plant being a guini pig would take care of the problem. If not, then I figure it could be anything else from winter sun, to a draft, to a skip in watering,or just a natural thing for older leaves to die off, and not fertilization problems since all other trees are so happy.
Do I sound stupid, or should I just not worry?
Did I make sense??lol
Thanks all

If only a few lower leaves are yellow, not to worry.

Use an all-round fert according to directions and forget about any fix-it concoctions.

Thanks all!!! Always can depend on great folks for a hand in looking at things logically!! :-)