A tree injection device configured to inject a solution into a tree has a head defining an input opening for receiving the solution and a shank. The shank has a generally circumferential surface elongated along an axis and extending from the head to a pointed end opposite the head. The generally circumferential surface has a radially constricted section positioned between a first radially enlarged section and a second radially enlarged section. The first radially enlarged section and second radially enlarged section have substantially equal diameter. An output opening for delivering the solution is defined by the radially constricted section and is in fluid communication with the input opening by a passageway defined by an interior of the shank.
