I have a Camphor tree in my backyard. The tree is approximately 50 feet tall wit a 4 foot trunk diameter. I recently pruned a large limb from the tree because it was in the way of a small deck I am going to build around its base. The limb is approximately 15 inches in diameter. I did not cover the cut with pruning paint. Several weeks later I noticed that the leaves on some of the limbs were turning brown. This process seems to be spreading to other branches of the tree. Is there anything I have done to endangering the life of this tree and if so what can I do to correct whatever damage I might have done?
That's a big camphor tree, you are fortunate to have a specimen like that. You should be consulting with a local certified arborist on major pruning and construction in the root zone, or you could very well be endangering the life of the tree.
Lack of pruning paint is not related to the leaves turning brown. Use it for cosmetic purpose but it does not have much to do with the tree health.
Have you started digging footings for the deck structure, and if so have you cut roots? If so, that is the most likely reason for browning and branch die-back.
The 15" limb you have removed is huge, and that type of extreme pruning can cause physiological stress.
If you have the resources for professional help, I would recommend that you contact an arborist/plant health care specialist for urgent assessment and stress management treatment. Bartlett Tree Experts is a national company with PHC specialists.