I cut out some fairly large scrub trees (Mulberry mainly) that were growing amongst a rather thick Hicksii Yew hedge. Absolutely no way to pull them out or dig them out. I'd like to apply something to the stump to permanently kill these pests (Without harming the Yew.). The electric company is cutting down a ton of trees around here and it looks like they are painting/ applying some sort of blue colored solution to the stump. Copper sulfate solution to inhibit suckering? I dont need much, any recommendations?