A wedge shaped bluff plate air-assisted sprayer: II. Spray deposits on lucerne (Medicago sativa L.)

G.O. FurnessA, M.M. WearneB, J.J. HastingsC, P.S. BartonD and C.B. DysonE

A South Australian Research and Development Institute (SARDI), Loxton Centre, PO Box 411, Loxton, South Australia 5333, Australia.

B Monsanto Australia Limited, 19 Wilton Terrace, Torrensville, South Australia 5031, Australia.

C Ian Macrow Consultants, 323 Margaret Street, Toowoomba, Queensland 4350, Australia.

D Altona Street, Abbotsford, New South Wales 2046, Australia.

E SARDI, Plant Research Centre, Hartley Grove, Urrbrae, South Australia 5064, Australia.


An air-assisted boom sprayer, consisting of a wedge shaped bluff plate placed in front of a spray boom, was used to evaluate deposition of a fluorescent pigment spray on lucerne. Slotted rotary sleeve atomizers were used in conjunction with the bluff plate. Results were compared to a conventional (non-air-assisted) spray boom with flat fan nozzles.

The amount of pigment deposited was greater using a bluff plate than non bluff plate treatments. However, the extra pigment deposited was confined to the lower side of the leaf in the top region of the crop. In all other sites, the amounts deposited in bluff plate and non bluff plate treatments were similar. A comparison of the amount of pigment deposited was also made using slotted rotary sleeve atomizers spinning vertically vs horizontally with the bluff plate. No significant differences were found.

The implications of the deposit patterns for efficacy, and the potential for improving spray penetration and coverage uniformity within the plant canopy with a bluff plate sprayer by modifying the air movement patterns behind it, are discussed.


Plant Protection Quarterly (2001) 16 (2) 84-87.