Is it too late to spray bagworms (the kind that look like pinecones) and save my emerald green?

I thought I had accidently sprayed the bottom of my tree with weed killer (vinegar). Upon closer inspection last night, I have bag worms. This morning I sprayed them with a Bonide product with BT. However, now I read it's too late in their life cycle for BT to be effective.
Any suggestions?
Only a portion of the bottom of the tree has browned. Do you think the tree can recover?
Many thanks!