After a banner pickup, the pilot of the PA-25-260 felt the "left rudder pedal become stiff" after the banner came off of the ground. The pilot looked back at the tail of the airplane and verified that the "hook rope" had caught the towrope and not the tail wheel of the airplane. After circling to the right in the banner pattern, the pilot decided to release the banner in order to "free up the rudder." He flew over the drop zone but was unable to line the airplane up so he activated the banner release handle over a grassy area that was free from obstructions or people, but the release was not successful. The pilot still had minimal rudder control and the airplane wanted to turn to the right. He then decided to land the airplane. After lining up with another grassy area he retarded the throttle and "stalled" the airplane into a "three point landing." The airplane then touched down, veered to the right, and impacted a berm substantially damaging the airplane. Post accident examination by a Federal Aviation Administration inspector revealed that the hook rope was wrapped around the rudder horn.