The pilot reported he was taking off on personal flight when a gust of wind lifted the airplane’s wing, and the airplane became airborne during his corrective control input. The pilot continued the climbout and attempted to gain airspeed, but the airplane did not accelerate and seemed to slow. The pilot elected to land the airplane to avoid trees that were ahead of him. The airplane touched down on a grass area just beyond the end of the runway but impacted in a drainage ditch about 100 ft. beyond the departure end of the runway that collapsed the nose landing gear. The airplane sustained substantial damage to the engine mounts at the nose landing gear. A Federal Aviation Administration inspector reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operations and that the engine was making power at impact. At the time of the accident, the pilot was taking off on runway 35 with a quartering wind from the northwest. The pilot reported that he may have encountered wind shear over the treetops which might have kept him low and slow to accelerate.