GM maize – Questions and Answers

Friday 28 May 2004

1) Has any of the maize seed been planted, and if so, where?

MAF originally identified 1,317 bags of maize seed which contained 0.05 percent GM presence, or less than 1 GM seed in 2000 non-GM seeds. Since our initial investigations we can confirm that 357 of the 1,317 bags of maize seed containing this very low GM presence were sold and nearly all planted. MAF has been able to trace all but one of these bags to Northland, Bay of Plenty, Waikato, Gisborne and Hawke's Bay regions. Several unplanted bags have since been seized and the seeds will either be destroyed or re-exported.

2) Has any of the planted maize been harvested, and if so, where is it now?

Yes, some of the planted maize has been harvested and made into silage. The silaging process destroys any seeds or viable plant material, meaning that corn plants do not grow out of the silage. This fact, mixed with the very low concentration of GM maize seed, means that there is little possibility of any GM maize surviving in the environment from this route.

3) What is happening with the maize that hasn't yet been harvested?

Some of the maize is being grown to produce grain for animal feed and has not yet been harvested.

MAF's job under the Hazardous Substances and New Organisms Act 1996 is to minimise any chance of GM maize surviving in the environment. While this risk is low because of the very small level of GM seed present in the maize, MAF has to assure itself that it is enforcing New Zealand's zero tolerance law for unapproved GM organisms.

MAF has determined that the most effective way to achieve this is to allow the normal harvesting and processing to occur with some additional conditions. This process will remove the maize seed from the property and "de-vitalise" any seed, which means the seed cannot germinate in the future.

MAF will follow-up with growers to ensure the conditions are implemented.

4) What exactly does "de-vitalisation" mean, and how will the harvesting process ensure no GM maize survives in the environment?

De-vitalisation removes the ability of the seed to germinate and form a plant. There are a number of methods commonly used by the grain industry to process maize seed so that it is de-vitalised: acid treatment and milling are the most frequent. The process of making silage also prevents seed vitality.

Maize seed (i.e. the kernels off the cobs) that is harvested for animal feed is milled and made into grain. The milling process involves drying and cracking the seed, which devitalises it.

5) When will the harvesting occur?


6) What is the risk of GM maize plants growing from material remaining in fields?

The risk of any GM plants surviving is virtually nil, because maize plants are dead when harvested, the nature of the harvesting process and the very low concentration of GM seed present.

When maize is harvested in the field, the kernels are stripped from the cobs. Any stray kernels that may be spilled into the fields are eaten by birds and attacked by fungi and other soil micro-organisms. Low soil temperatures at this time of year will prevent these kernels from germinating. .

7) What other measures will MAF be taking to stop GM from growing again in the same fields after harvesting?

MAF will include additional controls in the harvest process to minimise the probability of the formation of a self-sustaining population of GM Zea mays. Protocols covering these controls will be written and distributed to growers.

MAF will also perform follow-up visits to a selection of sites as part of validating its analysis.

8) What will happen to the crops once they have been harvested?

The harvested grain will be transported by truck to a processing site. The maize is first dried down to about 14 per cent moisture and then processed. At a minimum, the milling process splits the kernel and renders it non-viable. The maize may be coarsely or finely milled, depending on its intended use.

The maize will then be stored in secure, segregated storage to prevent it mixing with other grain. An additional cleaning protocol for processing sites will be required to minimise mixing.

9) Are growers allowed to sell the harvested material if it contains a GM presence?

Growers are able to sell harvested material for animal feed as long as there is no viable GM seed that could grow in the environment. Therefore, once this seed has been processed to non-viability, MAF believes that the material can be offered for sale by merchants as stock feed.

Food for human consumption must be labelled if the GM content of the food is approved and is more than 1 per cent. Even so, MAF understands that this maize was not grown for human consumption and it is very unlikely that it has been or will be directly consumed by humans.

10) What will happen to the seed that hasn't been planted?

This seed will be destroyed or re-exported.

11) What are the chances that this maize has cross-pollinated with other maize?

The chance of GM maize cross-pollinating with non-GM maize is very low because of the very low number of GM plants.

12) What were the GMOs that were discovered, and at what level?

In the larger consignment, the precise variety identified is Liberty Link T25, which is a variety of GM maize approved by Food Standards Australia New Zealand (FSANZ) for human consumption in New Zealand. Testing indicates presence is at less than 0.05 per cent. This translates to less than 1 seed in 2,000 or 50 plants out of every 100,000.

13) Does this represent a risk to human health or the environment?

There is no evidence of a risk to human health or the environment. The variety of GM maize detected in the large seed lot is widely grown in the United States and Canada. It is approved for human consumption in many countries, including New Zealand, although no one has ever applied to the Environmental Risk Management Authority to grow it here. Furthermore, it is present in low levels – fewer than 50 plants out of every 100,000.

14) Will growers and sellers be compensated for any loss of income?

The question of compensation is currently being worked through by MAF, the grain industry and Treasury. Until this analysis is complete, no determination on compensation is possible.

15) How do we test imports of seed for sowing?

The New Zealand GM testing regime is one of the strictest in the world.

MAF requires proof of testing for GM before seed can be cleared at the border for entry into New Zealand, and if there is any indication of GM content the seed is not allowed in. A consignment that has been tested offshore in a MAF-accredited laboratory, according to the method in our import protocol, will not be tested again unless there are genuine grounds to suspect that GM seeds are present. This means that seed from non-GM as well as GM producing countries are required to be certified GM-negative before it is allowed into the country.

In 2002, the sample sizes for testing for inadvertent GM content were increased from 1,400 to 3,200 seeds. This means that the current testing process gives MAF a high level of confidence (95 percent) that any consignment with a level of GM presence greater than one seed in a thousand will be detected.

13) Is a low level of GM presence inevitable?

With more and more GM crops being grown and traded around the world, there will be more opportunities for GM seeds to be present in seed supplies. On the other hand, the systems to separate GM and non-GM crops are likely to improve, driven both by commercial pressures and demands from governments for assurances.

It is very likely that there will continue to be incidents like this one, where GM seeds are present unintentionally at concentrations near the limit of detection. However, with appropriate actions and ongoing assurance systems, it should be possible to keep these incidents to a minimum.

14) Why doesn't New Zealand grow its own seeds?

New Zealand farmers use both locally produced and imported seeds. For pasture seeds such as ryegrasses and clovers, we are world-leaders – breeding and producing our own seeds and exporting about $60-70 million worth of them around the globe.

There are other reasons as well: some crops lose their vigour after several generations so new varieties must be imported from time to time, and many of the best seeds are hybrids that do not breed true – the next generation is unlikely to have the qualities that make the variety desirable.

New Zealand farmers realise that to be internationally competitive, it is essential that they can participate in the seed breeding and multiplication industry, which must import seeds.

For further information about MAF protocols visit:



Last Updated: 29 September 2010

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