We received an emailed question today from "Paul."
“My neighbor has two quaking aspen. The roots send suckers up in my yard
unmercifully. How can I control those suckers? I have tried round-up
concentrate. It kills the suckers but the roots do not seem to be affected. This
has been going on for years. His yard does not seem to be affected by new
sprouts shooting up in his lawn or flower beds.”
And how about the rapid growth rate of those suckers?! I wish my hair grew that fast.
Quaking aspen has a very shallow lateral root system and any damage to these roots will trigger the tree to send out suckers. So, if you aerate your lawn you may be hitting the tree’s roots ― even a lawn mower can trigger the production. You may also see increased sucker production if the homeowner next door prunes the tree or it is damaged in any way. It’s a result of the tree producing certain hormones when damaged, telling it to reproduce quickly.
For you, I don’t have good news.
Next time a sucker pops up, dig down to find the lateral root from which it’s growing. If it’s not too deep, you have one rather labor-intensive option: root prune as close as possible to your side of the fence and then trench and install a root barrier along the perimeter of your yard and the neighbor’s. The barrier will deflect lateral root growth into your yard.
Beyond that physical barrier, try spraying the rascals with Ortho’s Weed B Gone or Bonide® Sucker Punch. Cut the sprout before spraying it. Both of these products take some time to work (perhaps up to two weeks) so don’t give up if the suckers don’t die immediately. Alas, this is not a permanent solution. You will want to repeat the application per the instructions on the label. And repeat. And repeat. They will keep coming back, but in different locations.
If you don’t want to spray, you’ll need to be vigilant mowing, pulling or cutting the sprouts as they appear.
The good news here is that the quaking aspen is a short-lived tree. Patience, my friend.