The image you sent looks like a young, newly planted tree. Is this true? New trees planted in the desert really struggle the first few years as they adjust to high heat. Did it look fine before you fertilized? If so my guess is too much fertilizer especially for a new plant with young roots in a hot climate. Just wait. I suspect all the leaves will fall but when the cool weather returns in the fall you may see new growth. A mulch on top of the root zone to keep those roots cool might also help. The good news is once established your privet should adapt well. Standing water most of the day is not a good sign. Your soil should be draining better than that. Loosen the soil and add some organic matter and cut back the amount you water to half as much. Good luck! Keep growing, Marianne Binetti