While spraying a field, the agricultural pilot reversed course for another pass. During the pass, the pilot misjudged his altitude and impacted a tower with the airplane's propeller and inboard section of the right wing. As the tower fell, it separated the airplane's right horizontal stabilizer and right elevator. Unable to maintain altitude, the pilot performed a forced landing to a cornfield. The airplane came to rest in an upright position in an irrigation canal. The pilot reported that there were no mechanical malfunctions or failures with the airplane prior to the accident.