Answer: There are a few possibilities at work here that are probably combining to create the problem. First, you didn't mention what the sun exposure is, but just about anything against a wall and/or near pools in our area is absorbing brutal heat and light reflection. Western and southern walls are particularly intense as are areas around pool decks. Second, is the watering. With ANY plant in the desert, your goal is to water slowly, deeply and as infrequently as possible for that plant's needs. Desert soil and water both contain lots of salts, which can accumulate in the root zone over time. This salt buildup forms where the water stops penetrating. If you water plants lightly and frequently, salts will build up in the top layers of soil and damage or kill your plant. Salt burn often shows up first as browning leaves. Deep watering?or leaching?prevents this by flushing the salts past the root zone. It's essential that you allow your drip system to run long enough for water to penetrate the appropriate depth. Depending on the size emitters, soil type, etc. this might take several hours or even 10 hours. You can reduce the time you run the system by putting on extra emitters or changing to emitters with higher gallon/hour flow rates.
Use a soil probe (any long, pointed piece of metal or wood to poke into the soil) to check how far water has penetrated. The probe moves easily through moist soil, but stops when it hits hard dry soil. For your trees, water should reach about 2 feet deep, expanding to 3 as they mature. Water should be applied at the edge of any plant's canopy, which is where the feeder roots are taking up water. Emitters may have to be moved outward as the plant expands. Third, is the fertilizer. I don't recommend applying fertilizer for the first year after a plant is put in the ground, and almost never in the summer. Fertilizer is "forcing" the plant to grow, which is stressful, especially in the summer's heat. The plant is better off expending its energy on establishing a root system, rather than putting on new foliage. I'd suggest fertilizing in the spring. You didn't mention when you transplanted, but if it was recently, it is very stressful to plants to establish during the summer. Spring or fall is a better time. Finally, if you haven't already done so, put a thick layer of compost or mulch around the base of the plant to reduce moisture loss and soil temperatures, which will help the roots. Leave a few inches around the stem/trunk bare, as you don't want moist mulch rubbing up against the plant tissue. I hope this information helps! (If nothing else, remind to water slowly, deeply and as infrequently as possible!)
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