My dwarf lemon tree (planted in ground) was thriving for several weeks after getting it from the nursery. It is approximately 2 feet tall, and had large green leaves. It has experienced over the last couple of weeks severe leaf drop (leaves turn yellow from tip and then fall off), as well as stems are brown up to the the main trunk of the tree. I checked previous posts which indicated possible root rot, but digging down a few inches showed the root to be dry and whiteish, and soil to not be soggy. The soil is quite warm to the touch, even a few inches below. It has been very hot in southern CA, and I was away from the tree, so my boyfriend was watering the tree up to 3 times a day. There is a nearby sprinkler as well that provides some water. I have not watered it in the last couple of days for fear that it is actually some root rot that I was not able to find, but the soil does not seem wet. Any of you experts recognize this and can suggest a solution? Attached a few photos of leaves, branches, and root. Thanks!!