Royal Raindrop Crabapple issues
One of our two Royal Raindrops (planted in spring 2015) bloomed as expected this spring; however, its leaves never turned deep purple like the other one - they stayed reddish all summer long and are now wilting, turning orange and dropping. Any suggestions on the most likely culprit? Any hope for this tree or should we take advantage of our warranty and exchange it for another? Thanks!
Your tree is most likely water stressed. This summer we had unusually high temperatures and below average rainfall, which can lead to the issues you discussed. It is helpful to irrigate trees during times of heat and water stress, particularly when the crabapple fruit is growing and maturing. Here is a link to MU Guide G6879: Irrigating Trees and Shrubs During Summer Drought.