|My purple robe locust leaves are turning yellow and drying what is causing this?|
|Sounds like it might be water stress. If the soil is too dry, or there have been drying winds, the leaves can yellow and drop prematurely. Check to make sure there's not an invasion of whiteflies or aphids; their feeding can cause the leaves to yellow. Be sure to water your tree deeply once each week to compensate for the hot summer weather.
Best wishes with your landscape!