I planted 12 new trees few months ago, they were all doing great until recently. They all have needles and branches turning yellow to brown and falling off. Most of it is located on the middle and lower part of the plant. I've done a lot of research and can't figure out what the problem would be and what I should do. If anyone has any input, please share. I snapped few photos. I am in Boston, MA, winter is coming fast, need to protect these guys and hope for the best.

Thank you in advance!