".... my husband seems to think that the tree is not getting established. I think it's because we didn't cut the lawn back far enough. He bought a new tree from HD, but I think we should return it. What are your thoughts?...."

I agree you should have a well extending out 4 feet...grass retards growth by competition. But it will eventually (but slowly mature). I am also not a fan of rock mulch but this is dependent upon where you live.

Is there a lot of fruit drop or no flowers? If there are frosts during bloom you will not get fruit yields. Over fertilizing can cause lack of fruit as can lack of nitrogen. Generally I don't like to see fertilizer applied its first 3 years. Those leaves look pretty healthy, so I doubt lack of nitrogen.

Lack of watering can also cause fruit drop. Are you watering like it is grass? Citrus should receive infrequent but deep (down 2 feet first year and 3-4 feet afterwards in proportion to its crown diameter with a fairly decent drying out in between: soil probe hitting water level of about six inches before re-watering.)

meisocal, for the "black mold", that is most likely sooty mold, and could be an indication of aphids. I would give your tree a good hosing down, and make sure you control for ants, to keep them out of your citrus trees, and from farming the aphids (or possibly citricola scale, cottony cushion scale, mealybugs, whiteflies, or other phloem-sucking insects that excrete honeydew on which sooty mold fungi grow. Most likely aphids in our area, though.) Hose the tree down with a hard blast of water, paying particular attention to the tender new growth where aphids like to attack. You can also use insecticidal soap to kill aphids, which will not harm beneficials.

For your tree in the grass, you do always want to remove any grass out to and a little past the drip line of the tree (edge of canopy). I would consider mulching with wood chips or bark, and not stones if you can. It will provide organic materials as the mulch breaks down. I do fertilize my citrus, and especially my new citrus on a regular basis, about 4 times a year with a good quality citrus fertilizer with the proper NPK ratio and micronutrients. For me, on my thin soils (DG), it is important for my citrus to get a good start.

And you should water your citrus on a drip, and not via your lawn sprinklers. Citrus do not like to be hit by sprinklers, so if this is the case, I would find a better place to plant that tree, so it's not being hit by lawn sprinklers. This can eventually kill a citrus tree. Deep water about 18 to 24", frequently enough to keep that amount of soil moist (but let the top about 6" dry out between waterings to reduce soil-borne fungal infections from setting in), but not wet. The "deep watering" philosophy has been modified recently, as citrus feeder roots only extend about 18" below the surface of the soil, so watering any more deeply that that is simply a waste of water. This is UC Riverside's current teachings from classes I attended last winter (Tome Shea and Dr. Tracy Khan). I just use one of those cheap green plastic covered stakes, and periodically check my trees to make sure they are moist enough, deep enough. Now, the only exception to this would be areas with high salts in their soils (near the coast). In this case, an occasional very deep watering to help leach out salts that can build up in the soils is helpful. I find I do not need to do that with my citrus, but I DO need to do that with my avocados, as I'm only about 6-7 miles from the coast.

Questions & Answers to Citrus Management:
http://homeorchard.ucdavis.edu/files/140618.pdf

Patty S.

Here is a link that might be useful: UC IPM: Diseases & Disorders of Citrus Leaves & Twigs

Thanks for all the help.

Kaffir Lime - I have sprayed with some soapy water with a spray bottle and will let that sit until the next rain which is projected to be tomorrow.

Orange tree - I had been drip watering with a hose twice a week. It did get some water from lawn sprinklers' over spray, but that was not my primary method of watering. I feed it with some organic EB Orange/Avocado feed three time a year and also constantly add other materials (coffee ground, worm tea, worm castings) on top of the rocks. The rock are primarily there for weed control.

Anyway, hubby took out the tree this morning and we cut back the lawn to approximately 6 feet in diameter. He was right about the tree not being healthy. The roots did not go further than 18" down. We dug the planting hole to about 3ft and discovered that the soil is really clay mixed with lots of rock. The plan of attack is to mix in a mulch that helps loosen clay before we put the tree in. We could not get the hole much deeper because it was solid clay on the bottom. I wonder if we do need to take the extra step of digging deeper?

Instead of digging deeper, build upwards. A raised bed filled with top quality soil, mulched on top, would give your citrus a huge boost. The quality of native soil in CA is often very poor.