The pilot of an agricultural airplane reported that as he rotated the airplane for takeoff, the airplane felt “squirrelly”, and began to turn to the right. The pilot corrected for the right turn, and the airplane took a rapid left turn that he was unable to correct. At the edge of the runway, he pulled up, became airborne in ground effect, and headed for a row of trees. Knowing he was unable to clear the trees, he reached for the hopper dump handle; the airplane impacted terrain next to the runway and came to rest inverted. During the accident sequence the left wing separated from the airplane and the lower fuselage and right wing sustained substantial damage. The pilot reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. At the time of the accident, the pilot was taking off on runway 14. The nearest recorded weather observation reported winds from 010° at 13 knots.