On October 9, 1999, about 1300 Eastern Daylight Time, a Grumman G-164A, N7856, was substantially damaged when it impacted a moving motor vehicle, while departing from a dirt road near Burkittsville, Maryland. The certificated commercial pilot and the occupant of the motor vehicle received minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the aerial application flight conducted under 14 CFR Part 137.The pilot stated that all occupants of the property had been notified of the airplane's operations and that the area would be kept clear. The pilot did recall noticing a roadblock on the dirt road used for takeoffs and landings. On the twelfth takeoff from the dirt road, as the tail of the airplane lifted off the ground, the pilot noticed a truck driving towards him about 50 feet ahead. The pilot attempted an evasive maneuver to avoid the truck, but impacted the front bumper of the truck with the main landing gear of the airplane. The airplane nosed over the truck and came to rest inverted. According to the owner of the property where the accident occurred, the driver of the truck resided on the premises and was made aware that airplane activities were being conducted on the farm. The road that was being used by the airplane on the day of the accident was a private drive, and had been used on a regular basis for landing and departing airplanes. According to a Federal Aviation Administration inspector no mechanical difficulties were observed when the wreckage of the airplane was examined.