By Emily Flitter and Tom Polansek
NEW YORK/CHICAGO (Reuters) - U.S. weed specialists doubted on Friday that new federal restrictions on the use of a controversial weed killer, sold by Monsanto Co and BASF, will prevent recurrences next year of crop damage linked to the chemical.
The impact of the rules limiting sprayings of dicamba herbicides, announced by the U.S. Environmental Protection Agency (EPA), may affect Monsanto's biggest-ever biotech seed launch - soybeans engineered to resist the chemical.
The EPA's new limits focus on the application issues and do not address volatilization, herbicide experts and farmers said.
Monsanto proposed the changes and won support for them from the agency, according to a company statement.
Growers across the U.S. farm belt said this summer that dicamba affected areas other than where it was sprayed on the Monsanto soybeans, called Xtend, damaging millions of acres of crops that could not tolerate the herbicides.
Monsanto has blamed much of the damage on improper application of dicamba. Specialists, though, say the weed killer is risky because they can vaporize and drift across fields, a process called volatilization.
"Nothing in these new restrictions addresses volatility, and that's still an issue," said Aaron Hager, a weed scientist and professor at the University of Illinois.
Under EPA's guidelines, only certified pesticide applicators, or people under their supervision, will be allowed to spray dicamba formulations manufactured by Monsanto and BASF next year.
That restriction may not do much to reduce crop damage related to sprayings, though, because many farmers and commercial applicators are already certified, experts said.
The EPA also said it was trimming the hours during each day, and lowering the maximum allowable wind speed during which dicamba may be sprayed in 2018. Additionally, farmers must keep records proving they are complying with label instructions.
"Since we proposed this in a voluntary fashion, we're pleased with it," Scott Partridge, Monsanto's vice president of global strategy, said about the EPA rules in an interview.
DowDuPont Inc sells Monsanto's formulation under its own brand name. A BASF spokeswoman said the company was "pleased growers will continue to have access" to its herbicides.
The EPA will monitor the impact of the restrictions to help determine whether it should allow farmers to spray dicamba after 2018 on crops that have emerged from the ground.
"I hope it does a lot of good," Ples Spradley, a pesticide specialist at the University of Arkansas, said about the changes. "I have my doubts."
Jonas Oxgaard, an analyst for the investment management firm Bernstein, said the rules could slow the adoption of Monsanto's Xtend soybean seeds by making it harder for farmers to find times when they are permitted to spray dicamba.
For 2018, Monsanto predicts Xtend soybeans will be grown on about 40 million U.S. acres, or more than 40 percent of all soybean plantings. Oxgaard estimated Xtend soybean plantings at 30 to 35 million acres.
Dan Henebry, a farmer in Buffalo, Illinois, is among those who have ordered Xtend soybean seeds. He said he would plant them next spring under the EPA's tighter rules for dicamba use, but that the new restriction on wind speed will make it more difficult to spray.
"You're playing with Mother Nature," he said, "and some days she just does not cooperate."
(Editing by Jonathan Oatis and Bernadette Baum)