Depending on the size of the buckthorn infestation, it can be removed by pulling up the roots, cutting the stems or using specialized herbicides. For minor infestations, the most efficient way to remove buckthorn is manually. This works best when the seedlings are less than 3/8 of an inch in diameter. In this case, the roots should come out so the plant can't sprout again.
If the seedlings are too large to pull out by hand, using a hand tool designed to pull out shrub roots may be more effective. If there are too many of the plants to pull out individually, a better option may be to spray a herbicide, such as glyphosate or triclopyr, on the seedlings. Glyphosate should be carefully applied, as it kills all vegetation it touches. Triclopyr, on the other hand, targets only broad-leaf plants and does not harm grass if properly applied.
If dealing with large buckthorn plants, removal may require use of large hand cutting tools. Buckthorn plant stumps should be cut and then treated with a herbicide to prevent re-sprouting. This process should be done in late summer and throughout the fall. During May and June, buckthorn plants put out leaves, and herbicides are not as effective at this time. If there are only a few plant stumps to deal with, cover them with tin cans or black plastic to prevent re-sprouting.