Monsanto Co. is quietly mothballing its six-year-old  genetically modified potato, the first bioengineered crop it launched.

Monsanto, a St. Louis agricultural biotechnology and  herbicide company 85%-owned by Pharmacia Corp., of Peapack, N.J.,  confirmed Tuesday that it will stop selling genetically modified seed to  U.S. and Canadian potato farmers after this spring.

Launched in 1995, Monsanto's NewLeaf potato is  equipped with a gene from a microorganism to make a toxin that repels a  bug called the Colorado potato beetle. Monsanto advertised the potato to  farmers as a way to greatly reduce their spending on pesticides, but  NewLeaf never captured more than 5% of the potato-seed market.

Many potato farmers, hard pressed by a price-depressing glut of spuds, haven't been willing to pay the premium Monsanto  charges for its genetically modified seed. Meanwhile,  some food companies have shied away  from using the genetically modified potato to avoid getting  wrapped up in the debate over the safety of bioengineered food.

Last year, for example, fast-food giant McDonald's  Corp. told its french-fry suppliers to stop using the potato from Monsanto, the  only U.S. company to launch a genetically modified version of the tuber.  As a result, J.R. Simplot Co., a major maker of french fries, instructed its farmers to stop growing NewLeaf potatoes.

At its peak in 1999, NewLeaf potatoes were planted on  about 55,000 acres in North America. NewLeaf acreage shrank by roughly half last year. Monsanto's decision to add a new genetically engineered feature to its potato -- resistance to the Leaf Roll virus -- did little to perk up sales.

Monsanto spokeswoman Lori Fisher said the company decided several months ago to shelve the NewLeaf potato in order to focus its research and marketing funds on four far bigger markets for genetically modified seed: oilseeds, cotton, corn and wheat. Last year, for instance, U.S. farmers grew on 45 million acres soybean plants genetically  modified to tolerate exposure to Monsanto's Roundup herbicide.

"Potatoes are a great niche product," said Ms. Fisher. "We hope some day we can come back to it."

Monsanto said the dozens of employees who worked on its NewLeaf potato are being reassigned to other departments or have left the company. The NewLeaf marketing organization was based in Boise, Idaho, and field research was conducted in Maine.

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