COMMON BUCKTHORN (RHAMNUS CATHARTICA) is invasive through much of the United States. There is a link in my bio to the department of natural resources page for how to identify and your removal options as well. Here is the link: https://dnr.wisconsin.gov/topic/Invasives/fact/CommonBuckthorn people end up, leaving the shrub along the perimeter of their properties because it provides privacy from their neighbors. What I recommend you do is immediately plant tall, growing native shrubs, like dogwood