 give us a call at 800-760-9937. That's 800-760-9937. 800-760-9937. The National Corn Growers Association joined five other commodity groups in sending a letter to Commerce Secretary Gina Raimondo on possible herbicide tariffs. The groups are asking the secretary to consider the impacts on farmers as she reviews a petition by egg chemical company Corteva that would place duties on imports of the herbicide 240.