I have 2.5-3 acres land contaminated with buckthorn, multi-floral rose, and purple loosestrife, along with many more acres of neighboring acreage. I'm slowly making headway with physical removal of the buckthorn but I'm having mixed results with the "cut stump" treatment method using RoundUp. I have too many buckthorn trees to deal with so I can't be circling back for 2nd and 3rd applications. I am stepping up my attack and hope to get some advise. I'm planning to move to the basal bark method using Garlon4 (or generic version) and a backpack sprayer. It seems that there are many sprayers on the market so I am hoping to hear about what is good and what to avoid. I've read that Solo brand sprayers tend to be good. I'm not doing this as a profession but will probably be spraying for a few years so I would like something that will last and can be repaired. Any suggestions or info will be appreciated!