With Glyphosate (Round up etc) the finer the spray applied has a better effect, don't soak leaves, mix is 50/1 on normal 36% (?) concentrate. There is a battery (AA) operated attachment for a backpack that delivers a fine constant mist, you save money this way too. Personally I've gone organic except for under the trees that will be harvested, enjoy the colour & wildlife, no more soil erosion & when it gets too much strim it all down, takes just as long as constant spraying! My opinion anyway.
Paul