On June 20, 2004, about 0955 central daylight time, a Piper PA-25-235, N82451, collided with the ground while on approach to land on a grass strip near Gulf Shores, Alabama. The commercial pilot, the sole occupant, received minor injuries; the airplane was substantially damaged. Gulf Air Advertising was operating the airplane as a towing flight under the provisions of 14 CFR Part 91. Visual meteorological conditions prevailed, and a flight plan had not been filed. The flight departed Gulf Shores, Alabama, at 0820 on June 20, 2004. According to the pilot, he departed the grass strip and flew two separate banner flights along the beach. After dropping the second banner off he proceeded around the pattern to land on the grass strip. On the base leg of the pattern, the pilot states "a high enough speed was not kept and the right wing stalled and 'broke out' forcing the plane to the right and into a nose down attitude". According to a witness, the pilot was seen on its base to final leg when the airplane began going behind the tree line in a 90-degree bank and a 60-degree nose down position. The plane collided with trees in a nose down attitude and came to a stop upon hitting the ground. The pilot did not report a mechanical problem with the airplane during the flight.