GM research and plant adoption around the worldNo evidence of fungus link

Agrifood Awareness Australia

By Paula Fitzgerald, Agrifood Awareness Australia Limited

A report prepared for the US-based Council on Biotechnology Information outlines the breadth of genetically modified (GM) crop research being undertaken globally.

Unlike previous reports, which have focused on the commercial production of GM crops globally, this report investigates the research under way in the laboratory and field trial phase.

Genetically modified varieties of soybean, corn, cotton and canola dominate commercial production of GM crops, and they are largely grown in the US followed by Argentina, China, Canada and Brazil.

However, according to the report"s author, Professor Ford Runge, director of the University of Minnesota"s Centre for International Food and Agricultural Policy, 63 countries have been involved in some phase of GM plant research and development from laboratory and greenhouse experiments, to field trials, regulatory approvals and commercial production.

According to the report, the GM crop value reached US$44 billion in 2003- 04 in the top five producing countries and there are a number of GM crops which could be taken from field trial to commercial production very rapidly.

This would see the global area and value of GM crops continue to climb. Soybeans and maize in China are two examples.

The worldwide research and development effort involving GM crops is illustrated in the table.

Sixteen field crops have been the subject of research and development in 55 countries. These include lucerne, barley, canola, clover, cotton, maize, rice, sorghum, sunflower, wheat, lupins and mustard.

The characteristics being investigated of some global crops using gene technology were also outlined in this report, and will be included in the next issue of Gene Scene.

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Attention has been given in the media recently to claims of a link between the use of genetically modified (GM) glyphosate tolerant (marketed as Roundup Ready®) crops, including cotton, canola and soybean, and an increase in the prevalence of Fusarium fungus attacks in these crops.

The two GM crops of most interest in the Australian context are Roundup Ready® cotton, under commercial production, and Roundup Ready® canola, which has been approved by the federal Office of the Gene Technology Regulator for commercial release but is subject to state bans.

It has been alleged that in North America, glyphosate use on GM crops:

However, research has found that glyphosate-tolerant GM crops react no differently to disease than their non-GM counterparts.

Experiments involving glyphosate tolerant soybean in the US, both in the laboratory and in field trials, found that:

It has been suggested that changed agricultural practices in how herbicides are applied to herbicide-tolerant crops could increase infections by root pathogens. This is because weeds are routinely sprayed at a later stage in herbicide-tolerant crops and this may allow plant pathogens the opportunity to multiply in the dying roots of weeds and affect the crop.

While there is no scientific evidence to validate this claim, more research on the impact of changed agricultural practices on herbicide-fungal interactions is needed.

Treating crops with any pesticide, herbicide, fungicide or insecticide has the potential to alter soil microflora, but the level of disturbance is usually not of agricultural significance. However, research in this area suggests that it is possible to link an increased use of glyphosate with increased presence of soilborne fungal organisms such as Fusarium, depending on the frequency of herbicide use, agronomic factors and environmental conditions. Although detrimental herbicide interactions may occur, the frequency and severity of disease outbreaks are the result of other factors.

Recent research indicates that the effect of herbicide application, particularly glyphosate, on disease susceptibility is unlikely to be significant in the absence of other contributing factors, such as environmental conditions and the agronomic systems used to grow the crop. These factors are likely to vary widely.

The bottom line is that there has been no record of any fungal problems unique to the use of herbicides in herbicide-tolerant crops in the past decade. There is also no evidence that the growing of GM herbicide-tolerant crops poses any greater risk in terms of disease outbreak than use of their non-GM counterparts. Genetically modified herbicide tolerant crop varieties are no more susceptible to disease than their non-GM parents.

Although detrimental herbicide-disease interactions may occur, the frequency and severity of disease outbreaks are usually the result of other factors, and appropriate strategies should be in place to mitigate potential negative interactions.

The use of disease-tolerant cultivars is the most important element in reducing the incidence of soilborne fungal diseases.

For a number of reasons, including increased risk of weed resistance or of inducing a change in the weed spectrum, as well as possible implications for increased disease development, it is important that herbicides such as glyphosate not be overused.

(This article is based on a report by Dr J. L. Huppatz, Science Adviser, Agrifood Awareness Australia Limited.)

GRDC Research Code: AAA00004.

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Agrifood Awareness Australia Limited is an industry initiative established to increase public awareness of, and encourage informed debate about, gene technology. The organisation is supported by three peak bodies, including the GRDC.