A high pressure injection system for applying a pesticide includes a portable, handheld application tool and a manifold head connected to the application tool. The manifold head has at least one internal passage. At least one high pressure nozzle is positioned in the manifold head and in fluid communication with the at least one internal passage. The at least one high pressure nozzle is operable at pressures between about 25 psi and about 10,000 psi. A contact plate is mounted to the manifold head and has at least one opening aligned with the at least one high pressure nozzle. A source of pesticide is fluidly connected to the at least one high pressure nozzle. A discharge valve is moveable between a closed position wherein the pesticide is inhibited from flowing to the at least one high pressure nozzle and an opened position wherein pesticide flows to the at least one high pressure nozzle.