The agricultural industry in the United States has been threatened by weeds. Farmers are alarmed at the loss of chemical efficacy, especially in the Midwest.
A survey of large farm owners confirmed that agricultural production is increasingly challenged by ragweed, kochia and other weeds. The latter are already visibly crowding out crops within at least as many states as North Dakota, Iowa, Wisconsin and Minnesota. Experts say that often weed flora becomes resistant to the impact of several herbicide preparations at once.