Fine-tuning nozzle needs

Research is fine-tuning which spray nozzles are best suited for use with different types of chemicals when spraying cereal and canola crops.

Trials funded by the Grains Research and Development Corporation have confirmed that nozzle choice has a strong influence on where spray is deposited within a crop canopy.

Department of Agriculture and Food researcher John Moore, who led the research, said informed selection of nozzles could increase the efficacy of chemicals.

“Trials conducted in Western Australia in 2015 showed that conventional flat fan nozzles could be a better choice when spraying non-systemic chemicals (not translocated from the site of application) because they provide better coverage at all levels in the canopy,” he said.

Mr Moore said spray quality was a measure of the size and distribution of spray droplets produced by nozzles and for agricultural applications normally fell into fine, medium, coarse or very coarse categories.

“Some pesticides have a specified spray quality stated on the label and, for many products, finer spray qualities should not be used,” he said.

Mr Moore said of the conventional nozzles tested, the TCP 11002 nozzles producing a fine spray quality provided greater coverage at the top of the canopy and the 11003 nozzles produced a medium quality spray, providing better coverage throughout the canopy.

“AIXR 11002 air-induction nozzles produced bigger droplets corresponding to the coarse spray category and resulted in reduced coverage at all levels within the canopy. This would reduce spray drift, and could be appropriate where systemic, highly translocated products are used,” he said.

“The addition of spray oil increased droplet size and potentially reduced drift for medium XR 11003 nozzles but had little effect on the TCP 11002 or AIXR 11002.”

The field trials follow nozzle selection research led by J. Connor Ferguson at the Centre for Pesticide Application and Safety at the University of Queensland.

Mr Ferguson said a controlled spray drift trial at CPAS observed an 82 per cent reduction in drift when switching from the fine TCP 11002 to the coarse AIXR nozzle at 3 bar, and a 70 per cent reduction in drift switching from the medium XR 11003 nozzle to the coarse AIXR 11002 at 3 bar.

The spray nozzle research was part of the GRDC-supported project “Options for improved insecticide and fungicide use and canopy penetration in cereals and canola” involving The University of WA and the South Australian Research and Development Institute, as well as DAFWA and The University of Queensland.

The project is helping to identify spray application technologies that will reduce spray drift without reducing efficacy of fungicides and insecticides.