A US judge has banned growing genetically modified sugar beet in the United States until a more detailed investigation is carried out into its environmental impact.

That assessment could take until spring 2012, although the US sugar industry biotech council is hoping to work with the US Department of Agriculture to come up with interim measures that will allow growers to continue to plant GM beet crops in the meantime.

But if a temporary solution is not found the ruling is likely to cause major problems for beet growers and the sugar industry in the USA.

Judge Jeffrey White, of the federal court in San Francisco, California, made the ruling barring the cultivation of GM beet, which represent up to 95% of the US crop, on Friday, 13 August.

The order blocks farmers from planting the seed next spring, but leaves alone the crop already in the ground, which can be harvested this autumn, processed and sold as sugar.

Around half of the US sugar production is derived from sugar beet – the rest is from sugar cane. The US sugar beet crop was worth US$1.33bn (£850m) in 2007-2008.

GM beet is already planted on more than 400,000ha (1m acres) spanning 10 states, from Michigan to Oregon. All the seed comes from Oregon’s Willamette Valley.

This season’s crops could be the last to be harvested until regulators complete a more thorough environmental review of the biotechnology beet, which Monsanto developed to resist its popular glyphosate-based weed-killer Roundup.

Additional planting will not be allowed until the US Department of Agriculture completes the environmental impact statement, which commentators say can take two to three years.

The lawsuit against the USDA was filed by activist groups, including the Center for Food Safety and the Sierra Club, among others.

Critics worry that genetically modified beet would eventually share their genes with other sugar beet crops, or related crops of Swiss Chard and red table beet.

Sugar beet industry officials say it would be difficult for US farmers to switch back to non-GM seed, and it is unclear how much conventional seed is available.

The Sugar Industry Biotech Council issued a statement, saying they were working with the USDA to see if “interim measures” could be taken to continue the production of GM beets.

A council spokesman said: “The sugar beet industry will provide its full support to the USDA to allow full consideration of interim measures that will allow continued production of Roundup Ready sugar beet.”