Grains Research and Development

Date: 12.04.2016

Comprehensive study reveals cost of weeds to southern growers

Author: Sharon Watt

Looking over the cost of weeds report are GRDC Southern Regional Panel chair Keith Pengilley (left) and CSIRO research scientist Rick Llewellyn. Photo: Nicole Baxter, Coretext

Australia’s most comprehensive analysis of the cost of weeds in cropping systems has shown that the overall annual cost to grain growers in the southern cropping region is $1.6 billion or $150 per hectare.

The Grains Research and Development Corporation (GRDC) commissioned report Impact of weeds on Australian grain production also shows that growers are investing heavily in weed management and, despite increasing levels of herbicide resistance, in-crop weed populations are mostly being kept low.

GRDC General Manager Crop Protection Ken Young said the industry study into the cost of weeds – including yield losses and the costs of weed management practices – had input from 600 growers, as well as agronomists, consultants, agribusiness data experts and researchers.

“Weeds present one of the largest costs to grain growers and are one of the biggest influences on the management of cropping systems,” Dr Young said.

“This study is the most comprehensive review to date on the cost of weeds to Australian grain growers and the adoption of weed management and tillage practices, and will help guide future decisions on cropping systems research, development and extension.”

CSIRO Senior Research Scientist (Farming Systems) Rick Llewellyn, the lead author of the report, said key results at a national level included:

  • The overall cost of weeds to Australian grain growers is $3.3 billion annually
  • Weeds are costing Australian grain growers on average $146/ha in expenditure and yield losses
  • Average expenditure on weed control, including herbicide and non-herbicide practices, is $113/ha
  • Yield losses due to weeds amounts to 2.76 million tonnes of grain
  • The most expensive weeds in terms of total yield losses are annual ryegrass, wild radish and wild oats, with brome grass being a notable major weed that is increasingly costly.

The study, which was undertaken before the change in the boundary between the GRDC southern and northern cropping regions (all of New South Wales is now in the northern region and the southern region now comprises Victoria, South Australia and Tasmania only), has identified important differences between regions and agro-ecological zones.

The report has articulated the cost of weeds in southern agro-ecological zones, ranging from $105/ha in the low rainfall zone including the SA and Victorian Mallee and Upper Eyre Peninsula, up to $184/ha in the higher rainfall zones including SA’s Mid North, Yorke Peninsula and Lower Eyre Peninsula:

  • SA’s Mid North, Yorke Peninsula and Lower Eyre Peninsula (including the districts of Barossa, Blyth-Snowtown, Burra, Bute, Central Yorke Peninsula, Clare, Crystal Brook-Redhill, Eudunda, Hallett, Jamestown, Kapunda, Light, Mallala, Mount Remarkable, Pirie, Port Broughton, Riverton,  Robertstown, Rocky River, Saddleworth and Auburn, Spalding, North Wakefield-Burunga West, Pt Pirie Districts, Tumby Bay, Lower Eyre Peninsula, Central Yorke Peninsula and Northern Yorke Peninsula) – total cost of weeds is $319 million per annum or $184.35/ha
  • South-East of SA and Victoria’s Wimmera (including the districts of Peake, Naracoorte, Tatiara, Coonalpyn Downs, Horsham, Grampians-St Arnaud, Grampians-Stawell, Hindmarsh, West Wimmera, Yarriambiack South, Buloke South, Loddon and Campaspe-Rochester) – total cost $311m pa or $167.98/ha
  • SA and Victorian Mallee (including the districts of Loxton, Waikerie, Karoonda-East Murray, Lameroo, Mannum, Murray Bridge, Pinnaroo, Streaky Bay, Le Hunte, Kimba, Cleve, Ceduna, Yarriambiack-North, Mildura Buloke-North Swan Hill) – total cost $317m pa or $105.09/ha
  • Victorian high rainfall and Tasmanian grain production zone (including the districts of Campaspe, Hepburn West, Pyrenees North and South, Central Goldfields greater, Shepparton B West, Deloraine, Sheffield, Oatlands, Campbell Town and Bothwell) – total cost $52m or $161.62/ha
  • Victorian and NSW Slopes (including the districts of Cowra, Forbes, Parkes, Weddin, Boorowa, Young, Coolamon, Cootamundra, Junee, Lockhart, Temora, Wagga, Hume, Corowa, Culcairn, Holbrook, Urana, Moira and Wangaratta North) – total cost $357m pa or $165.09/ha
  • NSW Central (including the districts of Bogan, Cobar, Lachlan, Carrathool, Murray, Wakool, Balranald, Wentworth, Berrigan, Deniliquin and Jerilderie) – total cost $272m or $162.96/ha.

Dr Llewellyn said the costs of yield losses due to weed competition ($708 million nationally) were much lower than total weed management costs ($2.6 billion). “Reducing the cost of weed management is one of the grains industry’s largest challenges,” he said.

Dr Llewellyn said that as weed control through cultivation had declined, adoption by growers of a range of other weed management practices had increased. “Crop-topping, double knockdown and narrow windrow burning have increased, with the latter showing rapid recent increases in some areas,” he said.

The GRDC report Impact of weeds on Australian grain production is available at

The GRDC, which invests in grains research, development and extension (RD&E) on behalf of grain growers and the Australian Government, has a significant ongoing investment in the area of weed control and herbicide resistance. These investments include $45 million over five years into a ‘Herbicide Innovation Partnership’ with Bayer CropScience which aims to discover and develop innovative weed management solutions. The GRDC also has a $1.5 million annual investment in the Australian Herbicide Resistance Initiative (AHRI), based at The University of Western Australia.

Analysis shows that GRDC investment into the area of herbicide resistance alone over the past 25 years has returned a benefit-to-cost ratio of $3.50 for every dollar invested.

For interviews

Rick Llewellyn, CSIRO

08 8303 8502 / 0429 690 861

Ken Young, GRDC

02 6166 4500


Sharon Watt, Porter Novelli

0409 675 100