Stewrtia Japonica dying
 

Our Stewartia is in its third year outside of Boston. It had a few
blooms in July and looked health. It has been watered well but not to
excess. Suddenly last week all the leaves started turning brown. There
might be a borer entry near the ground and we applied some Sevin-5 to
the hole and on the ground around the trunk.

Can anyone guess what the problem might be?