The pilot stated he flew over the field to identify obstructions prior to beginning the spray passes. He noted a hog farm and powerline wires on the southwest side of the field so he decided to spray the field in a north/south pattern. The pilot began spraying on the east side of the field, and during the second pass, the airplane contacted a guide wire that extended from the row of powerlines, which paralleled his flight path. The pilot stated he did not see the guide wire while looking for obstructions. Upon hitting the wire, the engine lost power and the propeller appeared to feather. The pilot tried to gain altitude and was able to dump the remaining chemical load prior to the airplane impacting a corn field about ¾ of a mile from where it contacted the wire. The impact resulted in substantial damage to the fuselage. The pilot reported there was no mechanical failure/malfunction of the airplane prior to contacting the wire.