Still battling Bradford pear tree suckers

2½ years ago, we had a Bradford pear tree removed in our front yard because of severe mistletoe infestation that was causing limbs to break off. We replaced the tree with the giant clumping timber bamboo (Bambusa oldhamii) that has become the focal point of the front yard. Read this post for more information about this transformation.

The stump of the Bradford pear was ground out to a depth of approx. 2 feet—enough you would think to get rid of the tree for good. While that might be true for most trees, it clearly wasn’t enough to kill this one. Suckers started to pop up almost immediately, not only near the stump but many feet away.

 

My default method of control is to cut out the suckers with a hori-hori knife. In April 2011 I tried a product called Sucker Stopper RTU and while it may have slowed down sucker production for a while, it ultimately didn’t work. 

As you can see in these photos, there are so many suckers, I sometimes don’t even know where to begin.

 

Last weekend I cut out all the suckers I was able to spot—not always easy considering how many plants there are within 15 ft. of the where the tree had originally been.

 

The result is very satisfying.

 

No suckers, just stuff I planted, like these yellow-flowering pokers (Kniphofia citrina?)

 

Unfortunately, within a week or two the suckers will make a comeback. How much energy could possibly be stored in the remaining tree roots to still produce so many suckers???

Which brings me to the point of this post: Does anybody have any suggestions on how to eliminate these suckers once and for all? Would cutting the suckers near ground level and painting the cut surface with full-strength Roundup (glyphosate) work? I hate using chemicals in the garden but I’m running out of patience.