what do I do about yellow spots on my lemon and lime trees

Question

Lemon and lime tree, sporting yellow spots and leaves are falling off.
What is it?
What should I do about it?

Answer 1

Possible citrus canker:

https://www.gardeningknowhow.com/edible/fruits/lemons/common-lemon-tree-diseases.htm

https://edis.ifas.ufl.edu/hs141

http://ipm.ucanr.edu/PMG/C107/m107bpleaftwigdis.html