CHICAGO (Reuters) – An Arkansas task force has advised the state to bar sprayings after April 15 next year of agricultural herbicides with the chemical dicamba, which has been linked to crop damage across 20 states, a group spokeswoman said on Friday.

If adopted by the state, the recommendation would prevent most Arkansas farmers from spraying dicamba weed killers on growing soybeans, a key selling point for products manufactured by Monsanto Co, BASF and DuPont.

Last month, Arkansas banned the use and sale of dicamba after farmers complained the herbicide was drifting away from where it was sprayed into neighboring fields and damaging crops that were not resistant to the chemical.

The U.S. Environmental Protection Agency (EPA) also is reviewing label instructions for dicamba weed killers following the reports of crop damage.

Arkansas previously blocked Monsanto’s product, XtendiMax with VaporGrip, because of a lack of extra testing that state officials wanted. The state approved BASF’s product, Engenia.

Thirty-three other states — all the other states where the products were marketed — approved both products.

Monsanto said the recommendation by the Arkansas task force will put Arkansas farmers at a disadvantage to those in other states. The company said it was in talks with the EPA, which “is interested in achieving national uniformity with dicamba regulation in order to avoid a state patchwork.”

BASF and DuPont did not immediately respond to requests for comment.

The task force’s recommendation will be provided to Arkansas’ governor, agriculture department and the state plant board.