Piper PA-25-235 ZK-CIW

Piper PA-25-235 Pawnee B ZK-CIW (c/n 25-3323) was imported into New Zealand by the local agents, Airwork (NZ) Ltd of Christchurch.  It was registered to Aerial Sowing (Canterbury) Ltd on 09-09-1965. The photograph above shows it outside the Airwork hangar reasonably early in its career - before it was marked as "Aerial Sowing Ltd". At one stage it carried the name "Des Winter".
The photo comes from an unknown source.
Why the unusual wing tip (upper and lower surface) and lower rear fuselage colour ?

Photo below taken at Christchurch on 25-04-1966.

 Below we see her at Rangiora on 28-03-1972

And then again below at Christchurch on 26-04-1973. Both with Colin Sutherland's name behind the cockpit.

It was sold off to the Auckland Gliding Club on 11-08-1975.

Below we have her as seen by Peter Lewis at Ardmore on 25-01-1976

 Unfortunately it crashed after take off from Ardmore on 24-02-1979 killing the pilot James Neild.