You can spray them with Arsenal or a similar herbicide. But, it costs quite a bit for the spray, it works best during the early winter and fall time periods, and the stumps must be sprayed within a short time period of being cut. I think I read somewhere that you could spray the stumps as late as 3 hours after cutting. But, the sooner the better. They should be sprayed before they dry on the tops.

You may be able to re-cut the stumps and apply the spray. Your local extension agent or USDA representative could suggest some other sprays that will be cheaper. I am planning to cut and spray some stumps as part of a conservation plan this spring. I'll post on the results after I finish.