The pilot was a Chinese citizen who was being trained, as part of an Australian Development Aid program, to a standard equivalent to that required for an Agricultural rating. His Chinese Commercial Licence was suitably endorsed to allow training in this country. The flight in question was authorised as a practice spraying exercise and was to be the pilot's last solo sequence before a flight test. At the end of the first practice spraying run the entry into the procedure turn was delayed, and the turn was then conducted at less than the normal angle of bank. This placed the aircraft in a wide and low turn, during which it collided with a tree. This collision occurred at about 50 feet above ground level, and the aircraft struck the ground 35 metres beyond the tree. The pilot subsequently reported that the aircraft had been affected by a downdraft. However, other pilots and ground witnesses in the area indicated that excessive sink or downdrafts were unlikely to have occurred. The tree struck was prominent and contrasted well with the surrounding vegetation. It was likely that the pilot was looking back to check his flight path in relation to the spraying runs and had not seen the tree prior to the collision.