Q.CREPE MYRTLE YELLOWING, LEAVES FALLING PREMATURELY
100 or so year-old crepe myrtle is not performing this year. . . greened up as usual, then after three or four weeks, leaves started turning yellow and falling. Cause for alarm? Seems like it did this a couple of years ago but came back. The yellow leaves have little green spots all over. Wonder if we should spray or pray !

This could be watering issues, pests or disease.
https://www.gardeningknowhow.com/ornamental/trees/crepe-myrtle/crepe-myrtle-tree-problems.htm
https://www.gardeningknowhow.com/ornamental/trees/crepe-myrtle/crepe-myrtle-care.htm