I have an orange tree which is 15+ years old and the tree produces a lot of delicious oranges every year. Around mid of Sept this year, the tree started falling leaves on most branches on one side of the tree (picture 5320R and 5328R) which is facing east and south and a lot of the leaves are curled up now (photo 5331R).

Could anyone please help me diagnose my tree? Did I water too much or too little to cause the leaves falling and curled up? How could I cure the tree? We really love this tree and it has been with us for a long time.

I live in Phoenix, Arizona. Thanks a lot in advance!

Some of those curled leaves are probably thrips damage. My trees look like total garabge right now because of thrips. The August record heatwave really seemed bring out the thrips this year.

I'm not sure what to think about the leaf drop, but it's still holding on to a nice crop of fruit, so that's a good sign. It may be nothing to worry about. Are those branches still alive or are they dead?

Now that the weather has cooled, just continue to water like you always have at this time of year (at least for now), since you kept the tree alive and well for 15 years. I would also inspect the tree for signs of pests and inspect the bark, trunk and everything else for signs of disease or problems, including the watering area at the base of tree and canopy.

That's about the best I advice I can offer. Maybe someone else has a better answer.

If I remember correctly, the branches on a tree are served by the roots and vascular system on the same side of the tree.

IE, if there is a problem with the roots or trunk on one side of the tree, then the branches on that side will reflect it.

In your pic, the "bad" side is facing a wall, and I imagine the roots are running under that wall. Maybe a neighbor on the other side is doing something nasty to the soil on his side?

Post close-up photos of the trunk - particularly at the Y point and at ground level. It is these areas that are likely to be causing the problems higher up.

Mark_T, thanks for feedback. Actually, I did not notice any thrips on leaves. Do you have recommendations for how to inspect for pest and how to inspect for bark and truck?

The tree does hold a nice crop of fruit but a lot of oranges fell prematurely with leaves this year in the past a few weeks.

Cristofre, you are right, the branches facing south (wall) and east are bare now. My neighbor in the south side did trim a lot of branches facing them this year.

Here is the photo of the trunk (IMG 5338 and 5342) and want to make sure that it looks fine.

Two more questions

1. Do I need to trim/prune the seemed dead branches now?
2. If trimming/pruning is needed, when is the best time to do that?

Thanks a lot for your help!

ASU recommends pruning after the last chance of frost so late Feb, early March.

Someone else should chime in on the trunk, I don't see anything from the picture.

What is that black lump at the bottom of the picture?
Looks like it could be a filler, where a branch has been removed or rotted.
Could it be hiding further penetrating rot problems?
More pictures required of this area and down to ground level!