Posted: 30/06/2015 at 08:50
Sumach are well known for this trait unfortunately. You can either treat the individual suckers with weedkiller or when you cut your lawn you will cut the new growths and eventually weaken them.
It will probably take a long time by either method and you will need to be very vigilant in spotting any and every sucker. I have finally eradicated mine after 3 years.
Sumach are beautiful trees but they need to be planted with some care