The private pilot was conducting a normal aero tow takeoff in a glider from the 2,154 foot long turf runway 21. The tow plane pilot and the glider pilot both reported that they both became airborne at approximately 40 knots and both pilots released the tow rope at the end of the runway when it became obvious that the climb performance of the glider and the tow plane was insufficient to accelerate or to climb out of ground effect. The glider then crashed into the fence at the end of runway 21. Weather reported by at the time of the accident was 10 miles visibility, clear of clouds, winds from 150 at 9 knots, with a temperature of 74 degrees and dew point of 57 degrees. Density altitude was calculated as 2,260 feet. Other pilots familiar with this airport report that in crosswind operations there is frequently induced turbulence from the trees along left side of the departure end of runway 21.