A federal judge has ruled that the government failed to adequately assess the environmental impacts of genetically engineered sugar beets before approving the crop for cultivation in the United States. The decision could lead to a ban on the planting of the beets, which have been widely adopted by farmers.

In a decision issued Monday, Judge Jeffrey S. White of Federal District Court in San Francisco, said that the Agriculture Department should have done an environmental impact statement. He said it should have assessed the consequences from the likely spread of the genetically engineered trait to other sugar beets or to the related crops of Swiss chard and red table beets.

The decision echoes another ruling two years ago by a different judge in the same court involving genetically engineered alfalfa. In that case, the judge later ruled that farmers could no longer plant the genetically modified alfalfa until the Agriculture Department wrote the environmental impact statement. Two years later, there is still no such assessment and the alfalfa, with rare exceptions, is not being grown.

In the new case, Judge White has not yet decided on the remedy. A meeting to begin that phase of the case is scheduled for Oct. 30.