New Spraying Technique Shown

Press, Volume CVIII, Issue 31775, 4 September 1968, Page 14

New Spraying Technique Shown

A new technique of aerial spraying was shown to fanners, representatives of stock firms and officers of the Department of Agriculture and the Department of Scientific and Industrial Research at Rangiora Airport yesterday.

The larger size of the droplets distributed allows more accurate placement, and drift from wind or turbulence and loss from evaporation are reduced.

A new type of material and a modified spraying rig are used. The weedkiller or insecticide is distributed as a water-in-oil or invert emulsion. The oil with the active ingredient and the water are carried in separate tanks on the aircraft and are mixed continuously immediately before distribution, producing a viscous liquid which cannot be applied by conventional equipment. The spraying rig is fitted with special jets containing a series of calibrated holes. These form consistent droplets which fall like light rain. The system has been developed by Shell, and it was described by’ Mr S. Coles, agricultural chemicals adviser of the company. Mr J. Death, general manager of Aerial Farming of New Zealand, Ltd. who has been working on the development of the system in New Zealand, said that an aircraft using it could spray about 40 acres using about 2.8 gallons to the acre. Conventional spraying, using 10 to 15 gallons to the acre, would cover about nine acres.

There was also a safety advantage. A pilot who found himself in difficulty was reluctant to release material in a highly concentrated form. With the new system all he would have to release was a tank of water.

Before he took off in a Piper Pawnee to demonstrate the new process, Mr E. Ryan used the spray boom on the ground, the spray covering the ground like snow, as shown in the photograph above. Afterwards he made several runs over the airfield distributing the invert mater-

i ial and then water to demon- ■ strate their characteristics. i At question time some s doubts were expressed about ; the effectiveness of the i method where a good coveri age of spray was needed. ■ Mr H. Cox, research and deI velopment officer in the agri- • cultural chemicals division of

■ the company, said that this system was not a panacea. He s did not think it could be used I on every flying occasion. • Mr Coles said that higher ■ rates of application could be used. For some situations ■ more work would need to be • done to determine the mosl ' effective rates.