The airplane was departing from a 2,400 foot asphalt runway on an aerial application flight. The airplane was loaded to its maximum gross takeoff weight and configured with 10 degrees of flaps prior to the takeoff roll. The pilot reported that a tall stand of trees at the southeast side of the departure end of the runway blocked the wind and seemed to “create a void in the air” which resulted in an extended takeoff roll. Electing not to abort the takeoff, the pilot added more flaps but the airplane was unable to get airborne. The airplane went off the end of the runway, hit a ditch, and skidded across the road into a field. The landing gear separated from the airframe and the airplane’s fuselage and control surfaces sustained substantial damage. The pilot reported that the airplane did not have a mechanical malfunction during the attempted takeoff.