The tree is planted near the house on a west wall. I live in zone 9 with some coastal invluence i.e. fog, cool nights and seldom above 70 degrees daytime. The tree has only been in the ground (large pot before) about 2 years maybe. At first it looked way better. We had a very cold spell this past winter - freezing every night for almost 3 weeks). I don't think I feed it enough.
It also has what looks like black mildew on quite a few leaves. This is new this season. I have not seen that before. It only bore about 5 lemons and they were tiny...like they never matured.