The "score" was settled a while later when a RAAF exchange pilot stepped out of a kiwi Blunty after spinning it with too bang-water in the tips or not enough or something like that.
At least that's what the 'shaggers tried to pin on him at the time.
Conveniently the aircraft was destroyed and the fuel state could not be verified!!!
Just can't picture a low-wing type like the Cropduster rolling over on the ground when the spar broke upon a gear-up landing. Are you sure you're not confusing it with a Macchi which had a wing-spar fail in-flight?