Faced with snowballing numbers of complaints about misuse of the weedkiller dicamba, the Arkansas state plant board voted to temporarily prohibit farmers from spraying the herbicide on soybean and cotton crops. The board has received more than 240 complaints of damage to crops caused by dicamba drifting from neighboring fields; the bulk of them have come from three counties in northeastern Arkansas, just below the Missouri “bootheel.”
In some cases, damage was reported even when the herbicide was used properly, raising the possibility that the chemical is more difficult to control than had been thought. The events are being watched across the soybean-growing Midwest and South, where farmers are looking for new ways to control invasive weeds, such as Palmer amaranth, that are developing tolerance such standby weedkillers as glyphosate.
Dicamba damage, which threatens yields, was a problem last year in the mid-South but was expected to subside this year, rather than blossom, with EPA approval of low-volatility formulations of the weedkiller that were expected to be less susceptible to drifting. New GE strains of cotton and soybeans are available that tolerate dicamba. But older, more volatile versions of dicamba are still being used.
There are complaints of dicamba damage in other states but none on the scale of Arkansas. As for hopes of easy weed control, a University of Tennessee weed specialist said his experience showed that dicamba was an effective tool for controlling Palmer amaranth rather than a one-shot silver bullet. The weed is resistant to six classes of herbicide and can reduce soybean yields greatly if it takes over a field.
The 120-day emergency ban approved by the Arkansas plant board would increase, to $25,000, the fines that can be levied on growers for misuse. The next step is a review of the plan by Gov. Asa Hutchinson. If he approves the ban, the executive subcommittee of the Arkansas Legislative Council would put the rule into effect. “I have consistently supported the Plant Board in its protection of Arkansas agriculture, and I expect this recommended rule will ultimately go to the legislature for additional review and action,” Hutchinson said in a statement.
Earlier, the plant board said that only one formulation of dicamba, sold by BASF under the name Engenia, could be used on crops after April 15.
Some 242 complaints of dicamba misuse had been filed with the plant board as of Friday morning, up from 50 at mid-month. By comparison, there were 32 complaints of dicamba drift for all of 2016. Arkansas has strict regulations on use of the weedkiller because most soybean varieties are highly sensitive to the herbicide. Users are required to leave a 100-foot buffer around the edges of fields where dicamba is sprayed and a quarter-mile buffer between those fields and fields of sensitive crops downwind.
Tom Barber, an extension weed specialist at the University of Arkansas, said nearly all of the cotton and a significant percentage of the soybeans planted in the state this year are dicamba-resistant varieties. A University of Arkansas agronomist estimated that 40 percent of soybean plantings were of resistant varieties.
Early this month, Missouri agriculture officials warned farmers they could be fined $10,000—rising to $25,000 for repeat violations—for misusing a weedkiller that damages neighboring crops. Federal law also calls for severe penalties for using unapproved pesticides, said the state Agriculture Department. The state received 164 complaints of dicamba drift last year, concentrated in four counties in the “bootheel,” in southeastern Missouri. The complaints alleged herbicide drift damage to more than 41,000 acres of soybeans as well as peaches, tomatoes, watermelons, cantaloupe, rice, purple-hull peas, peanuts, cotton, and alfalfa.
Arkansas grew 4 percent and Missouri 6 percent of last year’s record-setting U.S. soybean crop of 4.306 billion bushels.