Following an explosion of complaints about crop damage by the weedkiller dicamba, the EPA strengthened its rules for spraying the herbicide onto genetically modified cotton and soybeans. The new guidelines require special training of applicators before they can spray dicamba, limit the time of day when it can be used and bar spraying when winds exceed 10 miles an hour, a reduction from the 15 mph limit this year.
The EPA said it will monitor the herbicide’s performance in 2018 “to help inform our decision whether to allow the continued ‘over the top’ use of dicamba beyond the 2018 growing season. In 2016, the agency gave dicamba, used in tandem with GE crops, a two-year registration.
Growers have embraced dicamba as a tool against invasive weeds that have developed resistance to widely use herbicides, including glyphosate. But many crops, including fruits and vegetables, are sensitive to dicamba and there were reports of dicamba damage to 3.1 million acres of soybeans this year. Some weed experts questioned if dicamba is too volatile to remain in use despite development of drift-resistant formulations.
Monsanto, which developed dicamba-tolerant cotton and soybean varieties, said it was “confident the required training and record-keeping can address the main causes of off-target movement.” The world’s largest seed and ag-chemical company says operator error is to blame in most cases of suspected dicamba drift rather. Among its steps to help customers, Monsanto said it would distribute spray nozzles specifically for use with dicamba.
The new EPA rules also apply to BASF and DuPont, which also sell dicamba. The guidelines require farmers to keep records of dicamba use and emphasize the risk to susceptible crops. By making dicamba a restricted-use herbicide, the EPA says applicators will be required to get training on how to use it.
Arkansas growers filed 985 complaints alleging misuse of dicamba this year, prompting the State Plant Board to propose a ban on using it on cotton and soybeans from April 16-Oct. 31 next year, effectively the growing season. The board scheduled a public hearing for Nov. 8 in Little Rock on the proposal.
University of Missouri weed specialist Kevin Bradley told Harvest Pubic Media that if EPA had not acted, “many state departments of ag would have taken these measures anyway.” Bradley said the new rules are unlikely to affect usage of the weedkiller.
Some 26 million acres of dicamba-tolerant soybeans and cotton were planted this year, says Monsanto, which expects a big increase next year.
To read an EPA Q-and-A on the revisions to dicamba regulations, click here.