We planted one Stag Horn about 5 years ago. We now have THREE huge ones. We discovered that one had spread it's roots into our flower box. We started digging and discovered that the roots had invaded our entire yard. They had gone under the concrete boundary from the side yard where we planted the first one, into our front yard; under the concrete barrier separating the side yard from the fields beyond, and into our alfalfa fields; and from the side yard under the concrete walkway which goes under our house foundation.
I have removed all the DG and the the ground cloth, dug up the original plant with it's huge root ball. I have pulled up the two other plants and all the major roots as well as the minor roots that I could find. However, some of the roots running under the concrete barriers and walkway I was unable to pull out and could only sever. I am also sure their are other roots I may not have found that are still in the ground, though all also severed.
Some of the large roots I have pulled out have clusters of white egg like sacks or seeds on them which look like they might produce more Stag Horns. So my fear is that any roots left behind, especially if they are like those, might start up knew Stag Horns and we may get another invasion. So if anyone has any suggestions on how to get rid of the roots that remain, those I could only sever and those that may still remain in the ground, I would love some advice.
I will be putting down two layers of ground cloth and DG and we will not put anything new in the area until next year - and never again a Stag Horn!
Desperately!! Sharon
@SFGiants2015 - Sharon. 
