The pilot in the tailwheel-equipped airplane reported that during takeoff from a private dirt airstrip which had a 3% uphill slope and was crowned in the center of the track, he struggled to correct for torque and P-factor and crosswind, and the airplane veered left. He was able to correct to the right and continued the takeoff roll. The airplane again veered to the left side of the airstrip and the left wing struck a tree. The airplane exited the left side of the runway and briefly ascended before descending into the brush where it came to rest. The airplane sustained substantial damage to the left wing. Additionally, the pilot reported that the accident could have been prevented had he aborted the takeoff sooner. The pilot reported that there were no mechanical malfunctions or failures with the airplane that would have precluded normal operation. The pilot reported that the wind was variable at 10 to 15 knots. The nearest Meteorological Aerodrome Report at the airport 14 miles to the east, reported that about the time of the accident, the wind was from 280° at 7 knots. The pilot used runway 34.