The helicopter pilot reported that, while conducting an agricultural application flight, he planned to fly over the top of the power pole. He applied full up collective to climb over the power lines, but the helicopter struggled to gain altitude. After clearing the pole, the main rotor speed got slow, the helicopter "quit flying", and he decided to conduct a run on landing on the field. The helicopter landed hard and the main rotor blades struck the tailboom.
The helicopter sustained substantial damage to the tailboom.
The pilot reported that there were no preaccident mechanical failures or malfunctions with the helicopter that would have precluded normal operation.