On March 25, 1998, at 0900 central standard time, a Grumman-Schweizer G-164B aerial application airplane, N6720K, sustained substantial damage when it nosed over during the landing roll on the wet grass runway at a private airstrip near Tuckerman, Arkansas. The airplane was owned and operated by Tuckerman Aviation, Tuckerman, Arkansas, under Title 14 CFR Part 137. The commercial pilot was not injured. Visual meteorological conditions prevailed for the local aerial application flight and a flight plan was not filed. The time of departure is unknown. During personal interviews, conducted by the investigator-in-charge, and on the Pilot/Operator Aircraft Accident Report (NTSB 6120.1/2), the pilot reported that during the landing to the south, the right main gear dropped into a mud hole underneath 6 inch tall Bermuda grass. The tire pushed up the mud, instead of rolling through the hole, and the airplane came to a sudden stop and nosed over to the inverted position. Structural damage occurred to the rudder, vertical stabilizer, engine and propeller.