Diquat is also a good trimming agent, but it is toxic. From what I understand, low rates of straight Triclopyr will kill only the branches it is sprayed on. Mixed with Picloram or Imazapyr and the whole tree goes.
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738