Hello, Thank you for contacting Ask Extension. Could you please send a few more pictures for me so that I can correcting determine what is going on? I need a picture of the entire tree, a picture  of the root flare and it's planting, and if there are more than one tree, can you send the same for those trees also? Also, can you send a picture of the area that these trees are planted at? this will help in analyzing the problem.

Hello, Thank you for contacting Ask Extension. Could you please send a few more pictures for me so that I can correcting determine what is going on? I need a picture of the entire tree, a picture of the root flare and it's planting, and if there are more than one tree, can you send the same for those trees also? Also, can you send a picture of the area that these trees are planted at? this will help in analyzing the problem.

Thank you for contacting Ask Extension. Bases on the information and pictures that you provided, it appears that the leaves could be suffering from leaf scorch. Leaf scorch occurs when water is lost from leaves faster than it can be replaced from soil. Any factor that interferes with either uptake of water by roots or movement of water throughout plants can cause water deficiency in leaves. The underlying causes of leaf scorch may be fungal or bacterial diseases (biotic) or environmental/ cultural problems (abiotic). 

I have included several publications for your reference:

https://plantpathology.ca.uky.edu/files/ppfs-or-w-17.pdf

https://mortonarb.org/plant-and-protect/tree-plant-care/plant-care-resources/leaf-scorch/

https://ipm.illinois.edu/diseases/series600/rpd620/