This was the first flight after removing the motor glider from storage and reassembling it. During initial climb, the glider started rolling left despite the pilots control inputs. He aborted the takeoff and landed straight ahead while attempting to maintain control of the powered glider. However, the left wing struck the ground and the glider began to cartwheel. The glider was substantially damaged and its pilot seriously injured. Examination of the flight control system revealed the left aileron connecting rod was disconnected at the fuselage/wing quick connection point and was undamaged. During assembly of the glider prior to the flight, the left aileron control tube was inadvertently not attached. The pilot did not verify that all flight controls moved free and correct prior to takeoff.