(Adds comments from Bayer in paragraphs 6-7)
By Tom Polansek
CHICAGO, Oct 31 (Reuters) - The U.S. Environmental Protection Agency said on Wednesday it would allow farmers to spray a controversial weed killer made by Bayer AG's Monsanto Co and BASF SE for two more years, with additional restrictions on use.
The agency said the herbicide, called dicamba, is an important tool for controlling weeds in crop fields.
However, the EPA said it would prohibit applications on soybeans 45 days after planting and on cotton 60 days after planting to address "potential concerns to surrounding crops and plants." The agency also limited the times during which dicamba can be sprayed.
The approval comes after two years of complaints by some farmers who said the weed killer drifted away from where it was sprayed on soy and cotton crops that Monsanto engineered to resist it.
According to farmers and agronomists, the chemical then damaged millions of acres of nearby crops and plants that could not tolerate it, including fruit trees and flowers. In the summer of 2017, this damaged an estimated 4 percent of U.S. soybean plantings.
Bayer and BASF say dicamba is safe when used properly and have attributed crop damage to user error. BASF did not immediately respond to a request for comment, while Bayer said it is planning to train farmers on the EPA's new restrictions.
"This continued registration, based on an extensive review, keeps this much-needed weed control tool in the hands of growers," said Ryan Rubischko, who heads Bayer's dicamba portfolio.
Farmers have been anxiously awaiting the EPA's ruling amid uncertainty about whether to order dicamba-resistant crop seeds to plant next year. Some weed experts and independent seed companies had called for the agency to pull the herbicide off the market, or only allow it to be used to clear weeds before crops are planted.
"By extending the registration for another two years with important new label updates that place additional restrictions on the product, we are providing certainty to all stakeholders for the upcoming growing season," EPA Acting Administrator Andrew Wheeler said.
Bayer bought Monsanto and its portfolio of dicamba-resistant soy seeds for $63 billion this year in a deal that created the world's largest seed and pesticides maker. The company sells dicamba herbicide, along with BASF and DowDuPont Inc.
Bayer is banking on its dicamba-resistant soybean seeds to dominate U.S. soy production. They are seen as a replacement for Monsanto's Roundup Ready line of seeds, engineered to tolerate the weed killer glyphosate, which has lost effectiveness as weeds develop tolerance to the chemical. (Reporting by Tom Polansek Editing by Richard Chang and Grant McCool)