GM crops: tools for insect pest and weed control in cotton and canola

Insect pests and weeds are a significant cost to Australian agriculture through reduced yields and the cost of control measures. Weeds are estimated to have caused an average loss of $3.9 billion annually over the period 1998–2002.

Modern biotechnology has developed genetically modified (GM) herbicide tolerant and insect resistant crop plants as new tools to reduce the adverse impacts of insect pests and weeds on production, improving the sustainability and productivity of Australian agriculture.

GM insect resistant and herbicide tolerant crops are particularly effective in integrated pest and weed management systems, where agricultural chemicals can be managed to minimise the development of chemical resistance and some other unintended impacts, including to non-target species and the environment. Additional benefits arise beyond insect pest and weed control, as explained in the two case studies below.

Case study: GM insect resistantand herbicide tolerant cotton

In Australia, GM insect resistant and herbicide tolerant cotton varieties have been grown since 1996 and 2000 respectively. Cultivation of these GM varieties has resulted in clear agronomic and environmental benefits for Australian cotton farmers.

Yield comparisons (1997–2005) show that yields from GM insect resistant cotton are similar to conventional varieties. However, the big benefit has been the reduction in the number of insecticide sprays on GM insect resistant crops (down by 75 per cent) and the volume of insecticide sprayed (down by as much as 85 per cent).

The types of chemicals sprayed—both insecticides and herbicides—have also changed. The evidence shows that insecticides used on GM insect resistant cotton tend to target the pest better, allowing beneficial predatory insects to remain in the crop. Reduced environmental impacts have been observed, for example lower levels of pesticide residues in rivers. Changes in the type and volume of pesticides used in GM cotton crops have reduced the estimated environmental impact of the industry.

The introduction of GM cotton varieties has also had social benefits. For example, the number of occupational health and safety incidents has fallen due to reduced pesticide spraying and hand weeding in cotton fields. Smarter use of chemicals by farmers has also improved community perceptions of the cotton industry.

Because of these benefits, 95 per cent of Australian cotton farmers grow GM varieties, accounting for more than 90 per cent of production.

The Gene Technology Regulator has approved GM cotton for commercial release in northern Australia, where previously it had been limited to regions south of latitude 22°S. GM cotton could provide a basis for the successful establishment of a cotton industry in northern Australia. In the past, insect pressures contributed to the failure of conventional cotton crops in the Ord River Irrigation Area in northern Western Australia.

Some of Australia’s export competitors have also adopted GM cotton. Reported benefits in the United States, India and China include increased profits, decreased chemical use and health benefits.

Case study: GM herbicide tolerant canola

Australian farmers have had access to two non-GM herbicide tolerant canola varieties (triazine tolerant and imidazolinone tolerant) since 1993 and 2000 respectively. Herbicide tolerant canola varieties enable better weed control and earlier sowing, taking advantage of the first seasonal rainfalls. They have also helped farmers shift to no-till or conservation-tillage systems, delivering environmental benefits such as reduced greenhouse gas emissions, reduced soil erosion and increased soil water retention.

GM herbicide tolerant canola varieties were grown commercially in Australia for the first time in 2008. Victoria and New South Wales were the first states to grow GM herbicide tolerant canola, albeit on a limited scale. Previously, state and territory moratorium legislation, introduced in all major canola growing states in 2003–04, had prevented commercial GM canola plantings. South Australia and Tasmania maintain their moratoria on the commercial growing of GM canola.

The primary benefit of GM herbicide tolerant canola will be the replacement of lower yielding, non-GM herbicide tolerant varieties with higher yielding GM herbicide tolerant varieties. GM varieties will also offer a greater choice of weed control options and reduce the environmental impacts of herbicide use by enabling farmers to use more environmentally friendly herbicides.

Canada is the world’s major exporter of canola and Australia’s main canola export competitor. Canadian farmers have reported increases in acreage, more effective weed control and the introduction of conservation-tillage practices as result of growing GM herbicide tolerant canola varieties. Canadian farmers have also reported reduced fuel use as a result of less tillage and fewer herbicide applications.

Challenges associated with GM insect resistant and herbicide tolerant crops

There are challenges associated with the adoption of GM insect resistant and herbicide tolerant crops. Managing the potential for insect pests to develop resistance to the active insecticide in GM insect resistant crops is a major challenge. For herbicide tolerant crops, the potential for weeds to become herbicide resistant is an important management challenge. Such challenges can and are being met through Integrated Pest Management and Integrated Weed Management systems, designed to maintain the sustainability of GM crops as new pest and weed control tools.

The future

Australian cotton and canola growers could benefit from the development of varieties that will deliver healthier oil profiles, increased water and nitrogen use efficiency, and those that will better tolerate the environmental stresses associated with climate change. Some of these characteristics may be developed using conventional breeding, whilst others may result from the use of GM technology.

More information on this topic is available in the report:

Holtzapffel, R, Mewett, O, Wesley, V and Hattersley, P, 2008, Genetically modified crops: tools for insect pest and weed control in cotton and canola, Australian Government Bureau of Rural Sciences, Canberra.

How do I find out more?

This brochure is one of a series of Biotechnology briefs on biotechnology and Australian agriculture.

Other titles in this series of Biotechnology briefs:

• GM canola: potential impacts on organic farming
• GM grains in Australia: identity preservation
• Market acceptance of GM canola
• GM canola: an information package
• GM crops in emerging economies
• Value of biotechnology applications to Australian agriculture
• GM oilseed crops and the Australian oilseed industry
• Genetically modified crops
• Australia’s crops and pastures in a changing climate
• Economic impacts of GM crops in Australia
• GM stockfeed in Australia.

The Australian Government’s National Biotechnology Strategy funded the production of these brochures and reports.

How can I get copies?

For a free copy of these and other DAFF publications please email Biotechnolgy.

Visit the Australian Government Department of Agriculture, Fisheries and Forestry website for regular updates and information on agricultural biotechnology: www.daff.gov.au/agbiotech.

We want to ensure that developments in biotechnology are captured for the benefit of the Australian community, industry and the environment, while safeguarding human health and ensuring environmental protection.