Experts and BHG readers answer.
Browning from lack of water usually shows up on the tips of the branches first, where the new growth is most tender. Browning on the interior of the shoots could be from insect or mite infestation. Check the leaves very closely for the presence of insects. (They may be small enough that it will be difficult to see them without a magnifying glass. If insects are present spray an appropriate insecticide to control them.