Def. not guava. We have those in Hawaii, they grow at low elevations. Can't remember the name. Try posting on the Hawaii forum.

If you scratch off the bark on one of the leafless branches and it is not green then I would remove the tree and plant another one or something else altogether. The spout looking thing next to the trunk is actually an emitter and it would be helpful for you to know how many gallons per hour it releases when it is on. My guess is that the emitter doesn't put out enough water for your tree, especially in the climate that you have. Additionally, with emitters, you have to make sure the area for water output is clear of hardened minerals from the water. If you have even slightly hard water, you will need to replace them every few years. The heads are inexpensive so it's no worries but it could be partially clogged leading to even less water getting to the tree. I know this has already been said but...please also be advised that the people at Lowe's aren't the best to ask complicated plant questions. Forget about asking anyone at Home Depot for sure.... Finally, whoever said about the guy wires being too tight is absolutely correct. You never want to have them that tight. The tree is likely getting strangled.

Your growing zone or location would be helpful, but looks like one of the silvery or variegated cultivars of Pittosporum tenuifolium, e.g., 'Silver Sheen' or some such.

above your hand ... everything attached by the green stem.. IS ONE LEAF ... it will all fall off in one piece ... and you will probably see the stem remnants if not previously cleaned up .... on the ground ... its called a compound leaf ... and very important to the ID process ... ken