The pilot landed on the landing strip. He was aware that the landing strip was wet, covered with grass and probably soft under the surface. The aircraft felt sluggish during the landing roll. Before attempting to take-off, the pilot walked along the length of the strip to inspect its condition. He assessed the strip as suitable for his operation. There was a slight across-strip slope and during the back-track taxi for take-off, the pilot moved to the up-slope, left side of the strip where the surface appeared firmer. Whilst watching out the right side of the aircraft at the take-off path, the left wing hit a small tree. He did not see the tree prior to the impact.
