August 7, 2003
Ministry of Agriculture and Forestry
today announced that it had completed its investigations into a
sweet corn crop grown at Gisborne earlier this year which was
reported to contain some GM material
unapproved for growing in New Zealand.
The investigations were prompted by a New Zealand company
alerting MAF of test results conducted in Japan by a food
service company that had conducted routine testing of a
proprietary topping mix. This mix contained sweet corn sourced
from New Zealand.
Testing completed at the AgriQuality GMO Services facility at
Melbourne identified the presence of a GM variety called Bt11 in
product samples but at very low levels – less than 0.1% or less
than one seed in 1,000. Corn product from
three of the four fields investigated returned positive tests
Bt11. Bt11 is a type of GM maize and sweet corn that has been
modified to be insect resistant and herbicide tolerant. Food
Standards Australia New Zealand has assessed this variety of
corn as safe for human consumption, although it is not currently
grown or sold in
MAF’s investigations as to the likely source of the GM
material involved analysis of
seed lines planted in the four Gisborne fields in question;
examination of all sweet corn and maize crops grown within 300m
of these fields; and a review of the harvesting and processing
systems used by the company.
MAF’s analysis of products taken from surrounding sweet corn
crops that flowered at the same time as the crops in question
has also produced negative test results for the presence of GM.
Similarly the review of the company satisfied MAF’s review team
that it was highly unlikely that the presence of the GM variety
resulted from mixing during harvest or processing of this crop.
Testing by MAF and the seed producer on the seed line grown on
all the four fields was negative but the
only known link between the fields is
the seed sown and therefore the possibility remains that the
imported seed was the source of the GM material.
second variety of sweet corn was planted on one of the four
fields in question. Because of this, MAF secured seed from the
same line from the company and arranged for this to be tested. A
positive test was obtained from this seed, but the concentration
is so small (less than 0.05% or less than five seeds in 10,000)
that the actual GM involved can not be identified.
MAF placed compliance orders on the four fields under
investigation. MAF and ERMA have reviewed post-harvest
management that was applied to these fields and concluded that
they are low risk. The compliance orders have now been cancelled
and the four fields approved for normal use.
MAF’s investigations have extended to determining the extent of
other plantings of the same two imported sweet corn varieties in
New Zealand last spring. These plantings comprised 98 fields or
775ha. Some of these fields have, subsequent to harvesting of
the grain, have either been grazed or have been planted in
Advice provided to MAF by specialist agronomists on all
plantings of these seeds indicates that there is an extremely
low risk of residual seed germinating to produce viable sweet
corn plants, due to the crop being harvested when the kernels
were immature and the post-harvest management systems involved.
MAF is working with industry to identify all the fields that
were planted from affected lines and is working with ERMA to
ensure that these fields are managed appropriately.
a precautionary measure, MAF has seized for destruction all
remaining seed from the original imported lines to ensure none
can be planted.
the light of these events MAF officials are now reviewing
testing procedures used for imported sweet corn and maize seeds.
The protocol is already very stringent and few changes are
envisaged. Nonetheless, options will be discussed with other
government agencies and stakeholders.
copy of the ministerial briefing document is available on MAF’s
web site, together with other more specific details of the seed
testing and field appraisals.
How can we be sure that the fields in Gisborne and others
throughout the country won’t produce more GM corn?
For more corn to grow there has to be
viable corn seeds or corn vegetation which can sprout into new
plants. No evidence of corn seed or volunteer plant growth was
seen either within the fields or within 3 metres around the
perimeter of the fields.
Each of the four fields in Gisborne had
visual inspections conducted by MAF. These inspections consisted
of systematic walking ‘sweeps’ of the fields using four-person
teams, which entirely covered each field. Inspectors were
looking for evidence of corn seed, remaining corn vegetation
(stubble) or growth of volunteer corn plants. The field teams
reported a high level of confidence that nothing was missed, due
to good visibility of the ground.
In addition, a leading
New Zealand scientist at Crop and Food Research, specialising in
maize and sweet corn breeding and growing, has provided MAF with
recommendations that specifically relate to the control of
volunteers in sweet corn fields. Based on this advice MAF
considers that the four fields have been subjected to
post-harvest cultivation treatments that would prevent any
viable material remaining in the fields. Harvesting also occurs
when the kernels are physiologically immature and therefore
The other fields throughout
New Zealand will be managed by a site management plan that will
address a range of potential scenarios and risk. The initial
indications are that many sweet corn fields are subjected to
post-harvest treatments that result in a low risk of volunteer
corn growing. Those post harvest treatments include measures
such as immediate cultivation after harvesting so that fresh
plant material is broken up and exposed to decay. Risk levels
are therefore very low as any residual seed heads that might be
present will be immature and because of mulching will not have
the opportunity to develop further.
2. What happened to the corn that was harvested from other
fields throughout New Zealand?
It is most likely that product grown in
these fields has been sold and consumed. If the product had
contained a presence of Bt11 sweetcorn, based on the extensive
testing done on other products, it is considered highly probable
that any level of presence would have been well below the 1
percent threshold for unintended presence allowed for in the
Australia/New Zealand Joint Food Standards Code.
Food Standards Australia New Zealand (FSANZ
), which administers the Joint Food Standards Code assesses the
safety of all GM foods before they are approved for sale. FSANZ
concluded in its safety assessment that food derived from Bt11
corn was safe for human consumption.
The New Zealand Food Safety Authority
therefore considers no further action is necessary in relation
to product grown from these fields.
3. Where were the
other fields located throughout
There were 16 fields in Gisborne, 74 fields in
and four fields in Canterbury.
4. What is the situation with further imports of seed from this
consultation with other government departments, is reviewing the
adequacy of the testing protocols used for imported sweet corn,
maize, oilseed rape and soya bean seeds imported for sowing.
Ministers will shortly be briefed on the conclusions reached.
5. Is there a tolerance or allowance for low levels of GM to be
imported into New Zealand?
No. The law does not permit unauthorised GM seeds to be
knowingly imported or planted. If GM seeds are detected, the
consignment will not be allowed into New Zealand. However, there
is always a chance that low concentrations of GM seeds may not
be detected. The limit of reliable detection is about 0.1
percent (one seed in a thousand). This is not a barrier between
what is detectable and what is not, but it indicates the level
where we can confidently find GM seeds. Lower concentrations of
GM seeds may be detected, but with much less confidence.
6. How are imports of seed tested?
testing regime is one of the strictest in the world. MAF tests
imported seed for growing in the environment at the border and
if there is any indication of unauthorised GM content it is not
allowed in. MAF requires all consignments of sweet corn,
maize, oilseed rape and soya bean seeds imported for sowing to
be tested for the presence of GM material
Last year 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 will detect the presence of 1
GM seed in 1000 with 95 percent confidence.
7. So why wasn’t the GM picked up in the import testing
Unless every single seed is tested (thereby destroying it), MAF
cannot guarantee 100 percent GM-free seed.
8. Why not stop all seeds from countries that produce GM
Banning imports of maize seeds would have serious negative
effects in several agricultural industries, including dairying
where green-feed and maize silage are widely used, but could
still not provide a 100 percent guarantee to stop all GM seeds.
Imported seeds are important for many New Zealand agricultural
industries – the price and quality of seeds affects the
competitiveness of these industries. For example, maize is grown
for food and is also an important stock feed in the dairy, pig
and poultry industries. Many of the best quality seeds come from
countries that grow GM crops, which are the world’s major seed
producers. Banning seeds from those countries would limit access
to those seeds and would probably raise the price of seeds,
which would negatively affect those industries that rely on
Although the costs of a ban are not clear, the value of these
crops gives an indication of their importance. MAF estimates
that the annual gross value of maize is about $70 million and
that it adds $60 million in extra production to the dairy
industry. The annual gross margin of the canola/oilseed rape
crop is about $1.8 million. New Zealand also has a seed
multiplication industry worth about $20-$30 million. This issue
highlights that as a trading nation, New Zealand faces both
risks and benefits from trade. In this case, the benefits of
importing seeds outweigh the risks.
9. Are GM plants already growing in
Testing at the border is rigorous and, when inadvertent GM
content is found, MAF acts immediately to control the situation.
With more and more GM crops being grown and traded around the
world, there will be more opportunities for inadvertent presence
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
is probably inevitable that there will be some instances of GM
seeds being inadvertently imported, but with appropriate actions
and ongoing assurance systems, it should be possible to keep
them isolated. There is always a chance that some low levels of
GM seeds may not be detected, but most of the time it will be
detected by the assurance systems that are in place.
MAF will investigate the suspected presence of any GM seeds as
it would for any other case where there is evidence of a breach
of the Biosecurity Act 1993.
10. Is there any connection between this event and Pacific
No. The two cases involve different GMOs and are kilometres
11. If we got another call from Japan would we go through this
For further information about The
New Zealand Food Safety Authority visit
For further information about MAF protocols visit: