Abstract: A tree injection device including a piston slidably received within a cylinder to define a piston chamber and a rack chamber within the cylinder, a reservoir in fluid communication with the piston chamber, wherein a first check valve allows fluid to pass from the reservoir to the piston chamber while substantially preventing fluid from passing from the piston chamber to the reservoir, an injector in fluid communication with the piston chamber, the injector being adapted for insertion into a tree, wherein a second check valve allows fluid to pass from the piston chamber to the injector, while substantially preventing fluid from passing from the injector to the piston chamber and a motor operatively connected to the piston to advance the piston through the cylinder.