The pilot carried out an inspection of a paddock and its surrounds prior to commencing the aerial application of insecticide. Three powerlines were identified, two within the paddock and another just outside a nearby fence line. The pilot reported that all three powerlines were checked for spur lines and T-junctions, as well as for aircraft clearance during the spray runs. The area in which the spray runs were being carried out was described as undulating, with a line of trees to the east, parallel to the flight path of the aircraft. Five spray runs were subsequently carried out in a north-south direction at a height of about six feet. This required the aircraft to be flown beneath the powerlines, the first of which lay in an east-west direction. On the sixth run, as the aircraft approached the first powerline, the pilot reported that he encountered some turbulence. The aircraft struck the powerline, but the pilot was able to maintain control and land on the property. A damage inspection by the pilot revealed that the right wing tip leading edge had been slightly bent, the windscreen was broken, and the propeller had sustained minor damage. He assessed that the aircraft was able to be flown to another location, where repairs were carried out. The weather was described by the pilot as fine, with a light south-easterly wind at approximately 8 kts, and scattered cloud.