The yellowish color of the leaves is called chlorosis. There are several causes. Have a soil test done to check the soil pH. If your soil is much above 7.0, the soil may need supplements of sulfur to bring pH down. Treatments for chlorosis may need to be done each year.
The browning is an indication the tree doesn’t get enough water, or is getting too much water. Trees need about 10 gallons of water per week, per 1 inch diameter of trunk. For a 4-5 inch diameter trunk, give 40-50 gallons per week, over several days, spread throughout the root zone, counting rainfall towards your total.
The lichen on the trunk may be an indication the tree is growing slower than average, a symptom of issues with roots, amount of water, compacted soil, nutrition levels in the soil.
The stone mulch raises the temperature considerably in the hot summer. Trees prefer a shredded or chipped wood mulch, and it improves the soil as it breaks down.
I can’t see the base of the trunk but, it should flare out at the soil level, not go straight in like a telephone pole. This is called the root collar (See picture below)
Years of growing under water and root zone stress and chlorosis means a shorten life for this tree. If you have these issues corrected, it probably can recover.
The results of a soil test will have a recommendation on how to correct the soil pH, if needed. Here is the link to getting a soil test- https://www.canr.msu.edu/resources/dont_guess_soil_test_get_your_home_lawn_and_garden_soil_test_kit_today
Hiring a certified arborist to go over the tree, check the root zone, excavate the root collar and aerate the soil, and apply amendments to correct the chlorosis, may be the most direct way to go. These are professionals who have taken training in care, diseases, pests and passed certification tests. He/she will come on site and give a complete diagnosis and a plant care plan. Find certified arborists by zip code here—-
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