Abstract: The system for injecting a systemic treatment liquid into trees and similar plants includes a plurality of substantially identical injector nozzles, each of which is insertable into one of a plurality of circumferentially spaced injector holes in the tree, a plurality of substantially identical sealed containers containing the treatment liquid in a predetermined quantity suitable for a single treatment through one of the injector holes and having a discharge conduit which is closed by a frangible member, a flexible strap or belt adapted to be wrapped around the tree at a location above the injector holes, a plurality of substantially identical connecting hose assemblies, each having one end adapted for connection to an injector nozzle and a connector at the other end which is insertable into the container discharge conduit and has a pointed outer tip for puncturing the container membrane, and valve means carried by each of the hose assemblies for selectively opening and closing the flow passage therethrough.