On June 2, 1993, at approximately 1330 central daylight time, a Grumman G 164B, N6695K, sustained substantial damage following a loss of control during landing. The commercial pilot was not injured. Visual meterological conditions prevailed throughout the area for the aerial application flight. During interviews conducted by the Federal Aviation Administration inspector with the pilot, the following information was revealed. The pilot attempted a downwind landing. During the landing roll, a gust of wind caught the airplane which subsequently impacted a dirt bank near the side of the runway. Upon impacting the terrain, the airplane nosed over. The pilot reported to the investigator in charge that he landed the airplane to the north in gusty crosswinds. He further reported that as he applied brakes, the airplane veered to the right, impacted a rice levee, and came to rest inverted. The pilot estimated the winds from the southeast at eight knots gusting to 12 knots. He also related that the left brake malfunctioned when he applied heavy braking in an attempt to stop.