The USDA’s Animal and Plant Health Inspection Service plans to prepare two separate environmental impact statements on genetically engineered crops from Dow AgroSciences and Monsanto.

The decision affecting Dow’s proposed 2,4-D-resistant corn and soybeans, and Monsanto’s Dicamba-resistant cotton and soybeans, appears to be a big setback to the companies, which had been working for the past several years to compile research data on the GE crops and obtain regulatory approval for commercial use.

Dow AgroSciences said it would continue to work with the USDA and APHIS to get the Enlist Weed Control System approved.

Dow said Friday that in the 4 years since it submitted a data package to the federal government in support of the Enlist traits, glyphosate-resistant and hard-to-control weeds have spread across the U.S. Twenty-five states are affected and the number of new acres infested in 2012 increased by 50% over the previous year.

“These adverse trends will continue without new state-of-the-art solutions like the Enlist Weed Control System,” the company says.

Monsanto will use the longer review time to improve its dicamba-tolerant corn and cotton by letting some farmers use the crops in its Ground Breakers program in 2013 and 2014, the company said in a statement Friday. Monsanto created dicamba-tolerant crops with BASF SE.

The American Soybean Association says the USDA’s decision could delay the introduction of new products containing these herbicide-tolerant traits to the market for an additional 2 to 4 years.

“Farmers rely on our federal agencies to make regulatory decisions based on sound science,” says Danny Murphy, a soybean farmer and president of the American Soybean Association (ASA) from Canton, Miss. “There is no reason for APHIS to conduct an additional EIS on top of the already-comprehensive environmental assessment that has been completed for these products.”

“USDA’s decision also greatly undermines its previous commitments to eliminate delays in its regulatory reviews and utilize robust environmental assessments.”

The USDA noted in its announcement Friday that these are the first GE plants developed to be resistant to 2,4-D and Dicamba, and that both products have been approved by the EPA, “and have been safely and widely used across the country since the 1960s to control weeds on crop and non-crop sites.”

APHIS says that for the 2,4-D resistant plants (one corn and two soybean varieties), the agency has previously made available for public review and comment petitions by Dow to deregulate the products, along with draft environmental assessments and plant pest risk assessments for two out of the three products.

APHIS received approximately 8,200 comments, including petitions signed by more than 400,000 people in response to these documents.

For the Dicamba-resistant plants (one soybean and one cotton variety), APHIS previously made available for public review and comment petitions by Monsanto to deregulate the products. The comment period on the petition for the cotton variety closed on April 29, 2013. APHIS has received more than 500 individual comments and 31,000 form letters regarding these two petitions.

Comments received in response to all of the 2,4-D and Dicamba documents have been similar in scope, ranging from the importance of making additional herbicide-resistant crops available for producers to focusing on the potential increased volume of herbicides containing 2,4-D and Dicamba and their movement onto non-target crops in surrounding areas, as well as the potential for the development of herbicide-resistant weeds.

APHIS says that under the National Environmental Policy Act, the agency is required to evaluate the potential environmental impacts that could result from a deregulation of new GE plants.

“With regard to these new herbicide-resistant plants, through its analysis of information submitted by the developers, as well as public comments, APHIS has determined that its regulatory decisions may significantly affect the quality of the human environment,” APHIS says.

APHIS' Notices of Intent to prepare these EIS's will officially publish in the Federal Register in the near future, and each notice will be accompanied by a 60-day public comment period. In preparing the EIS's, APHIS plans to host upcoming public meetings that will be publicized through the Federal Register and the Agency's Web site.