I have several Coast Redwoods on my property. I made the unfortunate mistake of cutting back the suckers near the base of the trees. Now I have a thick mat of suckers radiating 3 feet or so from the base of the trees. Some are growing above ground level on the trunk of the tree. I have tried covering them with tarps to block the sun (and photosynthesis) and using "Sucker Stopper RTU" (a plant growth regulator) to no avail. Any suggestions would be appreciated. I would really like to see the trunks of the trees rather than a mass of suckers.