(Adds details on lawsuit, comment from Monsanto, no comment from Arkansas)
CHICAGO, Oct 20 (Reuters) - Monsanto Co sued Arkansas agricultural officials on Friday to stop proposed restrictions on the use of a weed killer linked to widespread U.S. crop damage, setting up a legal battle between the agrichemical company and a major farm state.
Monsanto's lawsuit seeks to block the Arkansas State Plant Board from prohibiting the use of the company's dicamba herbicide during summer months. That is when the product is intended to be sprayed on soybeans and cotton that Monsanto has engineered to resist the chemical.
Growers across the farm belt said this summer that dicamba weed killers affected areas other than where it was sprayed on the Monsanto soybeans engineered to resist it, damaging millions of acres of crops that could not tolerate the herbicides.
Chemical companies have blamed crop damage linked to dicamba on farmers misusing the chemical.
Specialists, though, have said the weed killers are risky because they can vaporize and move across fields after they are sprayed on dicamba-resistant soybeans or cotton. That process, known as volatility, occurs more often in high temperatures, according to experts.
The U.S. Environmental Protection Agency (EPA) approved use of the herbicides on growing crops only through next year and could stop sprayings beyond 2018 if farmers suffer another year of damage.
Last month, the Arkansas plant board advanced a proposal putting the state just one step away from banning dicamba sprayings after April 15, 2018.
"The plant board's action disadvantages Arkansas farmers," Scott Partridge, vice president of global strategy for Monsanto, said on Friday.
Arkansas previously prevented farmers from using Monsanto's dicamba herbicide in 2017. The state allowed sales of a version made by rival BASF SE.
Terry Walker, director of the plant board, said on Friday he had not seen Monsanto's lawsuit and declined to comment. Board spokeswoman Adriane Barnes also had no immediate comment on the complaint.
The case is Monsanto Company v Arkansas State Plant Board et al, Circuit Court of Pulaski County, Arkansas, No. CV-17-5964. (Reporting by Tom Polansek; Editing by Diane Craft and Matthew Lewis)