Question
Hi sir, i have a river birch tree that is approximately 3-4 years old with an approximate height of 25'.

It has been thriving and doing so well where it is located and the leaves were healthy in appearance until i accidentally cut a large feeder root within 6" of the trunk base with my push mower.

I noticed harvester ants moved into this wounded portion of the root system; i have since then killed them off.  

My concern is shortly after this incident the leaves began to fall off over the entirety of the tree.  I am wondering if this wound will heal naturally and / or if my tree will be back strong and thriving next year?

I am concerned that the tree will not make it? Your suggestions and advice greatly appreciated.

Thanks a million, Chris
Eastern NC

Answer
Just cutting one root should not seriously damage the health of the tree. You will get some reaction for the root if some foliage dying back but the tree will recover quickly. Next spring the tree will leaf out fine with no signs of damage. I do not think you will have a problem.