I have an issue with some shrubs/trees not 'flushing out' with full leaves. I've been giving them regular deep waterings. Could this a pest issue or possibly a residual issue due to frost we had this past winter? Tree is a chitalpa, shrubs are yellow bells. Neither have flowered this season either. Yellow bell has regular leaves/branches on same plant that has stems with the under-developed leaves - any ideas on what could be causing this?

Other issue, lantana with infestation of white flies - probably 15 ft from these plants picture. Garden also seems stressed overall (more than just the heat, something else seems to be off in the yard, as most of my plants don't seem to be thriving when compared to this time last year.

Thank you in advance for any guidance/feedback offered.