I like an engine drive backpack for shrub treatments. That is different from the Stihl or Solo mist blower type units. Mist blowers are good for mosquito work and not much else. The engine drive backpacks can be regulated as to pressure and output. I have made many posts concerning this.
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