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Semi-concentrate Tree Spraying

Spraying apple trees with the Okanagan Turbo Mist sprayer at the Blackwood Experimental Orchard circa 1950. This sprayer which was imported by the Department of Agriculture around 1950 was the first semi-concentrate sprayer to be used in Australia and constituted a great leap forward for horticultural tree spraying in this country. With it the spray concentration could be up to four times the normal hand strength rate – the aim being to reduce the load of water needed in the sprayer as well as to apply a very complete cover of effective chemical over the foliage being sprayed.

The sprayer was a one-sided tractor pulled machine with a wind turbine and pump operated by a Wisconsin four cylinder petrol motor. The spray was delivered under pressure to seven nozzles designed to produce spray particles of a uniform size which were then picked up by the air stream from the turbine and carried into the trees. The rate of travel in the row was about 1.5mph (2.5kph) with the spray being applied to one side of a row of trees.

After extensive testing to make sure that the concentrated spray did not damage foliage and that the system was effective, the technique was adopted by an Adelaide firm Metters Limited, which produced its own machine for sale. Other manufacturers followed and double sided machines later became available together with PTO operated sprayers with adjustable jets to change the micron size of the spray droplets to cater for different crops and spraying situations.

(Source: John Steed)