Q.Desert willow
15 yrs old, 25w X 25H. Losing tops of limbs to summer storms. Need plan
Of action to maintain.

Tip dieback is a typical phenomenon; the dead
twigs can be easily pruned out in ornamental plantings
once the plants have leafed out in the spring. Irregular
growth requires attention early on to promote desired
trunk development. Desert willow may be pruned to form
a tree or shrub as desired. Since blooms occur on new
wood, the more it is pruned, the more it flowers.
Avoid over fertilizing, since this can send out long growth branches that don't withstand wind very well.
https://www.gardeningknowhow.com/ornamental/trees/desert-willow/caring-for-desert-willow-trees.htm