The pilot intended to spray a corn field and had discussed the location of power lines with his ground crew. As he approached the field, he observed power lines on 3 sides of the field in addition to a large set of power lines feeding into an adjacent substation. The pilot completed a 360° survey to identify the hazards including power lines, guy wires, and trees. During the survey, the middle of the field appeared to be clear. The pilot initiated an initial application pass and the helicopter struck a green wire, about 1/4" in diameter. The pilot’s efforts to maintain control of the helicopter were not successful, and it subsequently impacted the corn field. The helicopter came to rest on its left side with substantial damage to the fuselage, tail boom, main rotor blades, and flight controls. The pilot stated that there were no failures or malfunctions related to the helicopter before the impact with the power line. He also noted that the power line was green in color which was “practically invisible” with the background of the corn field.