This past winter, I removed a problem willow tree that was blowing so badly it threatened my house should it decide to fall. Shortly thereafter, I built a low deck, whose corner covers most of the stump to within about 10 inches of the top of what remains (which was about 18" high). I have removed trees before and stumps have just stayed that way - stumps. Willows, however appear to be a little more resilient than say, cedars or firs.
The willow has continued to grow despite my desire that it not, and I have dozens of new starts from the stump shooting up through and around my new deck. I have tried digging up the portions of the stump that I could reach and severing them from the roots, but that has been ineffective. I keep cutting them down every couple of weeks, but woudl like to find a more permanent solution.
What I need to do is find a way to kill the willow - roots and all.
If anyone is familiar with this problem, or just knows of somethign that will kill a large former tree, I would be very interested in hearing what you have to say.
Thanks