Not sure what the label for microlife says.

It looks like a magnesium deficiency to me on the IML, and generally under fertilized.

Not sunburn; they grow well in full sun in the tropics; possibly lack of water and apparently a lack of fertilizer.
You have to fertilize Meyers 3 times per year... I recommend January, May, and September; because the tree gets 85% of its food from the first 18" of soil. For quicker health, try a nursery foliar fertilizer applied every 15 days until they look more healthy... the color should be deep green.

Well, I see a few things that might be causing this. It looks like you've got a situation where you have a LOT of grass competing with both water and nutrients . You really do need to create a much large cleared area from underneath your little trees. Grass is a huge nitrogen hog. It will simply gobble up all that nice fertilizer you're putting down for your citrus. Not familiar with that particular fertilizer, but you'll want a fertilizer formulated for citrus, that is higher in nitrogen and also contains a good amount of micronutrients as well as your NPK macronutrients. And if your trees are being sprinkled by your lawn sprinklers, this is NOT good for the trees. This actually can eventually kill a small young tree. They don't like their trunks sprinkled. You'll want to put your trees on a drip system, and give them a long, deep drink one or twice a week (depending up on how hot it gets.) Doesn't look like sunburn, and yes, young citrus trees can get sunburned if you live in very hot, dry, sunny areas (like AZ, interior S. California). I agree with John's recommentations, fertilize at least 3 times a year - I fertilize 4 times a year - February through September/October. And, I use a foliar fertilizer especially if we've had a cold, wet winter and spring, which for me tends to make micronutrients unavailable since my soil is mostly DG. Grow More Citrus Growers Blend is a great product, and can be applied both to the roots or as a foliar spray. Spray in the evening.

Patty S.

Thanks for the replies. Im going to do alittle widening of the beds and fertilizer. Thanks again for recommendations!

Mgk65's post is correct. It is very easy to see that your tree is deficient in magnesium. Applying fertilizer does not help the situation, as almost all fertilizer formulations do not contain magnesium. Dissolve a tablespoon of Epsom salts, which is Magnesium Sulfate, in a gallon of hot water, and pour the cooled solution over the root area. Do this once a week until the deficiency clears up.