The private pilot reported he was landing the tailwheel-equipped airplane on a gravel-covered runway in a left crosswind. He said that he used insufficient rudder on touchdown, and that shortly thereafter the airplane "curved" to the left. He stated he added power to correct the situation and abort the landing, but the airplane's right wing contacted trees and brush "well below flying speed" and pivoted to the right. The airplane continued to track right, exited the gravel runway, and came to rest at the base of an embankment. The airplane sustained substantial damage to the left wing assembly and empennage. The pilot noted that there were no mechanical anomalies with the airplane during the time frame of the accident. The airplane was operated as a personal flight under the provisions of Title 14, Code of Federal Regulations Part 91, when the accident occurred.