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!!
I'll start by saying I'm not an expert. You've confirmed that the roots are not mushy so my guess would be the problem is under-watering. The soil appears to be composed of a large quantity of small rock aggregate with little material that would retain moisture. The exposed roots at the top add to the problem. Then there's the sun and heat which would increase the tree's demand for moisture. All considered it's not too surprising that the tree is stressed.
First off, were you able to confirm that problem was due to a lack of moisture? Did the tree recover or at least stabilize when you gave it more water? If so, then you can consider amending the soil. My experience with citrus is limited to culture in containers indoors so I can't really comment on soil amendment. However an online search turned up the following document which contains some suggestions under the heading Planting Citrus: Homeowner Citrus in a Greening World - UF/IFAS Extension Lake County
I, too, am no expert on growing citrus but the symptoms you describe lead me to believe your tree is reacting to the shock and stress of being planted in the ground after living in the coddled conditions the pot provided. It has not had the opportunity to grow roots into the new environment it now finds itself at a warm, dry time of year. At this point, I would dig it up and put it in a generous pot of good soil and give it time to recover. Keep the soil moist; do not fertilize. Let it catch its breath and then, when it seems in better health, plant it out again the coolest, wettest time of year.
