Q.Tree pest ?
Hello i was wondering if you could help me figure out what is wrong with my orange blood tree if it is a pest or just smething that can be fixed…..it is potted and the problem i saw it sinced i bought it ,but had never seen one this big so hoped it would not progress as i had one before and it kept going i war until it all died….the tip of the branches start getting brown, dried out/dead and it continues moving inward on my last tree it was in the ground and same thing happend even thought i cut of those parts (althought i havent cut alot or it almost just the dead part and a little of green ) it kept spreading until it died and i am devastated this would happen, it is sprouting new leaves but the branches are having this problem, and its lost almost all of its leaves i am in zone 10 san diego, CA the days are sunny and just starting to get cold at night, hope you can help i am devastated each time i prune, the tree has a strong trunk like 3 inches width i am attaching a picture , my dad loves this fruit so i got it for his birthday and hope you can help me figure out what to do ,please

The symptom you are seeing is called twig dieback. This could be caused by one of the diseases discussed in these articles:
http://ipm.ucanr.edu/PMG/C107/m107bpleaftwigdis.html
http://ipm.ucanr.edu/PMG/r107100111.html
http://cals.arizona.edu/pubs/diseases/az1154/
For proper diagnosis, you may need to ask a local extension agent for help. They will have better knowledge of the citrus diseases common in San Diego.