Arkansas State Plant Board votes unanimously to ban dicamba after April 15

The Arkansas State Plant Board voted Thursday afternoon (Sept. 21) to limit the use of the herbicide dicamba to before April 16, 2018, despite a chorus of farmers asking for a cutoff extension. A 30-day public comment period will be held and a public meeting will be slated for Nov. 8, according to the Arkansas Agriculture Department Executive Subcommittee. The final proposed rule will then be forwarded to the Arkansas Legislative Council for approval. State lawmakers will also consider raising the violator penalty from $1,000 to $25,000.

“They (the board) relied heavily on the task force’s recommendation … the Plant Board has spoken,” Arkansas Agriculture Department Director of Communications Adriane Barnes told Talk Business & Politics.

A petition by Monsanto to reject the task force’s findings was denied by board members. The petition claimed the findings of damage caused by dicamba were not steeped in scientific consensus, and proper application and use resulted in positive growing results. The petition stated there is no evidence the damage done to non-dicamba crops will result in yield losses.

A new regulation that establishes notice procedures for requesting additional research and for restricting products beyond EPA approval will be considered, too. This regulatory change will be subject to a 30-day public comment period which will be followed by a public hearing to be held in conjunction with the Board’s next quarterly meeting on Dec. 12. Following the public hearing, the final proposed rule will be forwarded to the Arkansas Legislative Council for final rule approval.

A petition supporting the use of dicamba signed by about 300 farmers was presented to the board prior to its decision. It asked the cutoff date to be extended to May 15, 2018, and they agreed to a one mile buffer zone around areas where the herbicide is applied. It also laid out time of day application restrictions and further restrictions when temperatures rise in the late spring. The farmers also proposed that a web site be built showing the public all fields where dicamba will be used. The farmers advocating the web site work on about 1.2 million acres.

The state instituted a 120-day ban on July 11 after a slew of damage complaints. Scientists, farmers, and others with an interest in the use of the herbicide were appointed to a task force by Gov. Asa Hutchinson and others. Farmers need to know by October what chemicals will be available for the upcoming growing season.

Dicamba is used to kill weeds, especially the pigweed, in row crops. It’s primarily used in soybean and cotton production. Arkansas farmers planted 3.7 million soybean acres this year, making it the 11th largest soybean producing state. In May, ASPB began receiving numerous complaints about crop damage from suspected dicamba drift. It received 963 damage complaints from 26 counties, mostly in Northeast Arkansas where the herbicide is used at a higher rate. It is the most complaints the ASPB has ever received in one year. Dicamba has been banned in several states.

Dicamba has been used as an herbicide for more than 50 years to manage 200 broad leaf weeds. It is a Weed Science Society of America Group 4 synthetic auxin – a plant hormone that causes plants to exhibit uncontrolled growth, according to the University of Arkansas. Dicamba works by mimicking auxin, a plant growth hormone, disrupting cell division. It is more volatile in warmer climates.

ASPB decided earlier this year to allow one formulation, Engenia dicamba, to be used in the state to fight pigweed, an aggressive weed that has plagued farmers in recent years. About 35% of the state’s 3.5 million soybean acres were planted with genetically-altered dicamba tolerant seeds. About 75% (300,000 acres) of the state’s cotton crop was planted with dicamba resistant seeds.

Scientists theorized dicamba was drifting into adjacent crop fields, gardens, and other places. Misapplications, weather conditions, or some other unknown factors may have caused the alleged drift. Tests proved the new formulations were less volatile than older ones, but there was still volatility, and it could last up to 36 hours after it was sprayed. Dicamba can attach to dust particles, meaning it can travel much further from target sites than previously thought.

Some additives enhanced the volatility. Ammonium sulfate and glufosinate increase the damage capabilities of dicamba. Researchers found damage could spread up to 220 feet away from an application site, nearly double the buffer distance the Environmental Protection Agency requires between dicamba and non-dicamba fields. Tests showed that if the wind blew in one direction for several hours, drift could cause damage on adjacent fields and then if the wind changed hours later, the same amount of damage would be caused there.

How this will impact yields is still unknown. Rate of exposure, how many times a plant has been exposed, the growing stage of the plant at the time of the exposure, environmental conditions, and others will have to be factored. Some studies have shown a late-season replant can cause lower yields than allowing a damaged plant.