Abstract: An apparatus and method is disclosed for injecting a treatment liquid into a hole drilled into a trunk of a tree comprising a container for receiving the treatment liquid and a closure for closing the container. A one-way valve means enables a pressurized gas to be introduced into container. A control valve controls the flow of liquid from the container into a flexible tubing. The flexible tubing has an injector nozzle for insertion into the hole in the trunk of the tree for enabling the pressurized gas to force the treatment liquid into the hole in the tree to administer the treatment liquid thereby.