Pesticide spraying guidelines part of national best practice for cotton growers
Pesticide spraying guidelines developed by University of Queensland Gatton College researchers are part of new best practice management principles for Australia's cotton growers.
The Centre for Pesticide Application and Safety (CPAS) received close to $850,000
in program funding from the Land and Water Resources Research and Development Corporation, the Cotton Research and Development Corporation and the Murray Darling Basin Commission over six years to investigate pesticide spray drift.
The research team, led by CPAS director Nicholas Woods, investigated endosulfan spray drift in the main cotton-growing districts of New South Wales and Queensland. Endosulfan is used by growers to kill the caterpillar stage of the heliothis moth.
Their results were included in the Best Management Practice Program, also known as the Good Neighbours Program, for the cotton industry, launched last month in Goondiwindi by New South Wales and Queensland premiers Bob Carr and Peter Beattie.
The researchers focused their laboratory and field studies on river and waterway (riverine) areas in the MacQuarie, Namoi and Gwydir valleys in New South Wales. Main towns in the area include Warren, Narrabri and Moree.
Cotton is Australia's fourth largest rural export worth $1.5 billion a year. The nation's 1400 growers produce three million bales of cotton each year with 95 percent of production exported.
Mr Woods said his team, of CPAS research officer Dr Ian Craig, senior research assistant Gary Dorr and research assistant Matthew Jones, first analysed laboratory droplet size data from the wind tunnel testing of nozzles used on Australian agricultural aircraft. This work was conducted in conjunction with "Spraysearch", Victoria.
The next stage involved measuring droplet movement during aerial spraying using 20-metre-high towers topped with string or copper wire to catch residues. The towers, mounted on trailers, were positioned both inside and outside cotton fields. The commercial application of insecticides was monitored as well as spray drift arising from controlled field experiments.
"Mathematical models using both CPAS software and overseas software were
then developed and compared with field results to describe the spray drift process. We then formulated guidelines to help cotton growers modify spray regimes in order to reduce spray drift," Mr Woods said.
A key change involves modifications to the nozzles used on aircraft to distribute pesticides, according to Mr Woods. "The nozzles we recommend distribute larger droplets but in greater volumes so as to achieve the same coverage - the underlying principle being that larger droplets fall to the ground faster and can be used to mitigate off-target downwind drift," he said.
The guidelines also contained recommendations on optimal meteorological conditions, in-crop buffer distances (to catch spray fall-out) and aircraft calibration details for the aerial application of pesticides, he said.
For more information, contact Mr Woods (telephone 07 5460 1293, facsimile 07 5460 1283, mobile 018 708 392 or email nicholas.woods@mailbox.uq.edu.au).
