The pilot reported that while performing aerial application operations and flying under power lines, the airplane propeller struck a power line. Subsequently, the airplane vibrated excessively and the pilot performed an off-airport landing at a farm field.

The pilot further reported that during the landing roll, he could not maintain directional control of the airplane on the rough terrain; the airplane veered sharply to the right and the left wing impacted the ground.

The left wing sustained substantial damage.

The pilot reported there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.