Olive Tree in Container Losing Leaves

[LayDee gardener]

I work as a housekeeper on a country estate and the lady has two large mature olive trees in the conservatory. One has always seemed a bit more stunted than the other, but this year some of the leaves on a whole stem are just curling up and "eventually dropping off " if I shake the tree. I check it's moisture level with a reader and it doesn't seem too dry or wet. it is solid in the pot, so very difficult to see anything and much too heavy to get it from the pot. I have already cut quite a lot off, and it know I'm going to get hauled over the coals for this, but I really don't know what the problem is and what I can do. The leaves are also going a brownish green. I have uploaded a couple of photos for any assistance with this! Thanks in advance.

[tomc]

At a guess only; when were they last repotted?

This may be outside of your pay-grade.

I would consult with the owner.