The U.S. Department of Agriculture plans to have interim rules governing genetically modified sugar beets in place by the end of the year after a judge revoked the government's approval of the plants last month.

The USDA also said it is giving priority to completion of a study on Creve Coeur-based Monsanto Co.'s Roundup Ready sugar beet seeds for potential reapproval within two years. A federal judge last month threw out approval of the crop for commercial planting, saying the department hadn't properly considered potential environmental effects.

The actions announced Wednesday by the USDA respond to the concerns of producers while complying with the court order, Agriculture Secretary Tom Vilsack said in a statement. They also further USDA's continuing efforts to enable coexistence among conventional, organic and biotechnology production systems, Vilsack said.

The genetically altered sugar beets provide about one-half of the U.S. sugar supply, and some farmers have warned that there aren't enough conventional seeds and herbicide to fill the void. The scientific seeds account for about 95 percent of the current sugar beet crop in the U.S.

The judge's decision does not affect crops planted before Aug. 13, allowing this year's plantings to be harvested, stored and sold.

The Associated Press contributed to this report.