suckering blackthorn

[charles]

 I know the problem well. All kinds of wild plum, sloes, blackthorn are inveterate suckers and over a long distance BUT if the parent plant has gone, the remaining roots will eventually run out of energy if you keep mulching and cutting them. The mulch you suggest will probably not kill them but will have a good weakening effect, and keep pulling or cutting any new growth you see. You could try digging out the roots (I wouldn’t!) but there are probably a large number of them, quite deep, and it is simpler to let them fade over a couple of years.