We are not able to accurately identify the tree from the photo. We would like to have more information. Please send us photos in focus of the whole tree, around the base, and  close up views of the foliage so we can see what you are dealing with. 
 Please also include information on the age and location of the plant and soil and site conditions, how you care for the plant, etc. 

Here is a link on tips for submitting photos https://extension.umd.edu/hgic/tips-submitting-photos-ask-extension

There may be several reasons for browning such as poor site conditions, girdling roots, drought, excessive moisture, etc. These are cultural and environmental issues. https://extension.umd.edu/hgic/topics/tree-and-shrub-problems-not-caused-disease-or-insects-abiotic
When subject to these factors, trees can be susceptible to possible insect and disease issues. 

Marian