A new tree dies of thirst long before it dies of anything else.
Most tree companies do not do irrigation. I do. In Riverside it is not a side service, it is the difference between a tree and a stick.
The usual story is a line that was fine for years and is now reaching three of the four places it used to reach. Nobody notices until something browns off, and by then it has been dry for a month.
The other story is a tree that was just planted. Getting water to the root ball for its first two summers is most of the work of keeping it, and it is worth sorting out on the same visit rather than the one after.
Something browning off for no reason?
Say which zone and how long it has been doing it.