* Farmers asked to exchange seed containing Duracade trait
* Duracade corn plantings seen below 300,000 acres in U.S.
* Gavilon, in deal with Syngenta, to accept crops with trait
By Tom Polansek
CHICAGO, Feb 21 (Reuters) - Archer Daniels Midland Co , one of the world's top grain traders, said on Friday it will not accept crops containing a new genetically modified Syngenta AG corn trait until major importers approve the strain.
ADM said it will not take any commodity with Syngenta's Agrisure Duracade trait for domestic processing or export, joining rivals Cargill Inc and Bunge Ltd which have signaled they will limit their handling of the product.
Corn seeds containing the Duracade trait are available for planting in the United States for the first time this year after U.S. authorities cleared the strain in 2013. The trait has not been approved for import by China or the European Union, both major buyers of U.S. crops.
"For now, we reserve the right to test deliveries and decline those that contain Duracade," ADM spokeswoman Jackie Anderson told Reuters.
The commercialization of Duracade has split the U.S. farm sector and pitted global grain merchants against Swiss-based Syngenta, the world's largest crop chemicals company. Some U.S. growers have said they want access to the new trait, which is engineered to fight pests called rootworms, while exporters warn it threatens to disrupt trade.
ADM's decision was another blow to Syngenta after Cargill, the top exporter of U.S. grain and oilseeds, said last week it will not accept crops containing Duracade for delivery against export contracts. Bunge has signaled it will not handle crops containing the trait until it is cleared by major overseas buyers.
GMO crops are controversial because critics say they are harmful to the environment and that food made with them can be harmful to humans.
ADM said it was asking farmers to try to exchange any seed they had purchased for planting this spring that was not approved for all major export markets, including China.
"We recognize it's an extra step, but we're confident it's in the best interests of everyone involved in U.S. agriculture," Anderson said of the move.
Syngenta on Thursday said grain trader Gavilon, owned by Marubeni Corp, had agreed to accept Duracade "at market price while providing stewardship and distribution services for producers." Representatives of Syngenta and Gavilon did not immediately respond to questions about the deal on Friday.
The agreement will help balance farmers' access to new seed technology with "maintaining markets for U.S. corn," the National Corn Growers Association said.
Still, grain traders are wary of the new trait following China's rejection of more than 600,000 tonnes of U.S. corn and corn products containing another unauthorized GMO Syngenta corn trait, Agrisure Viptera, since November. Known as MIR 162, the trait has been awaiting Beijing's approval for more than two years.
The National Grain and Feed Association (NGFA) and North American Export Grain Association last month asked Syngenta to suspend the commercial use of Duracade and MIR 162 in the United States until China and other export markets have granted regulatory approval.
Duracade already has approval from buyers including Mexico, South Korea and Japan.
Syngenta has declined the groups' request, saying the trait will be available in limited quantities and that growers need new technologies. The company has not said how many acres of U.S. farmland it expects to be planted with corn seeds containing Duracade.
During a meeting with NGFA representatives in December, a Syngenta representative estimated Duracade could be grown on as many as 700,000 acres, the association said. However, "recent indications from other sources" indicate plantings may be somewhat less than 300,000 acres, according to the group.
Corn was planted on 95.4 million acres in the United States last year.
Even if corn containing Duracade is planted on a small number of acres, it could accidentally be shipped to China, exporters have said. Varieties are often mixed with each other because they are grown in fields close to each other and then harvested, transported and stored together.
"Accidents happen no matter how rigorous a stewardship program is," NGFA President Randy Gordon said in an interview.