In what could serve as a cautionary tale to those who relish the prospect of a regulatory bonfire in Britain post-Brexit, independent researchers and state officials in the United States have raised the alarm over new herbicides, which appear to be killing crops in fields close to their points of use.

A number of US States have mounted investigations in response to increased reports of damage to arable fields, horticulture crops and even orchards, which farmers are linking to the licensing last year of three new herbicides containing the active ingredient dicamba.

Monsanto’s new version of the dicamba herbicide, the most famous of the new preparations, is designed to be used with genetically modified Roundup Ready 2 Xtend seeds, which have been engineered to withstand applications of the new product.

Farmers believe that the damage is occurring as a result of drifting herbicide, which is affecting non-target crops. What’s more, news agency Reuters last week drew attention to the approval process for Monsanto’s new herbicide, highlighting that Monsanto submitted its own safety studies to regulators, but refused to allow independent testing of volatility or drift, and noting that the US Environmental Protection Agency (EPA) did not challenge this. Researchers from three US universities told the press agency that samples of the new XtendiMax herbicide were provided to them along with contracts that explicitly forbade volatility testing.

The herbicide was designed to have lower volatility, and the EPA passed it for use last summer, with only the manufacturer’s test results supplied as evidence of this.
 
Monsanto maintains that its product should not be harmful to non-target crops when used correctly, and the company issued an open letter to its customers last week, in response to the growing controversy. The Missouri-based agchem giant said that, working with State authorities, it has trained thousands of farmers and spray operators in the correct use of its products. The letter reads, “We are hearing that the overwhelming majority of farmers are experiencing tremendous success during this first year of commercial launch. However, we have also heard reports that some farmers are noticing signs of leaf cupping in nearby soybean fields, which could be attributable to dicamba. Any time we hear reports of potential crop injury, from any cause, it concerns us.”

Monsanto said that, in response to concerning reports this growing season, it has set up a hotline for farmers experiencing damage, and that company agronomists are ready to meet with farmers to look at individual cases in the field. The company has also pledged to continue to roll-out training and is looking into whether “Unusual environmental conditions” could have affected applications of its new product this year.

States take action in response to widespread complaints

In Arkansas, which blocked Monsanto’s product after the company refused to allow independent volatility testing, but initially approved similar products from BASF and DuPont, state authorities have withdrawn approval for agricultural use of dicamba products; to date, there have been 864 reported cases of damage from dicamba herbicides in 26 counties, which the state Agriculture department is investigating.  

In early July, the state of Missouri also issued a temporary ban on the three dicamba herbicides after the state Agriculture Department’s Bureau of Pesticide Control received more than 130 pesticide drift complaints, alleging damage to thousands of acres of crops between January and July this year. The ban was lifted after just one week, once the Agriculture Department had established stricter conditions for use.

On 13 July, State Director of Agriculture Chris Chinn commented, “From the moment the stop sale and use order went into effect, we’ve been working to get these weed control products back into the hands of our farmers. BASF, Monsanto and DuPont came to the table and agreed to additional safeguards for product use in response to issues we’ve faced this growing season.”

Elsewhere, Nebraska’s Agriculture Department has said its pesticide and fertiliser programme staff are “actively investigating” an uptick in complaints relating to dicamba, though the Department “does not plan to limit use of dicamba… at this time,” and in Tennessee, the state Agriculture Department introduced new, stricter rules on dicamba applications, in response to complaints about damage to cropland, which state authorities said they are also looking into.

“Our approach will offer protection to those who stand to be negatively impacted by off-target movement of dicamba while also allowing those farmers who have invested in products designed for their crops to continue to use the appropriate herbicides responsibly,” Tennessee Agriculture Commissioner Jai Templeton said in July.

The three agchem companies whose products are implicated in the complaints have issued their own guidance for farmers using the herbicides, including stipulations on windspeed, boom height and appropriate nozzles. They have urged growers to consult state guidance in light of restrictions brought in by some state departments; in Missouri, only licensed spray operators can apply dicamba products, and they must do so only at certain times of day, having notified the state department and promised to keep their own records on each application. 

Last week, researchers from the University of Arkansas confirmed that new dicamba herbicides are volatile, though they are less volatile than older preparations that were banned for in-crop use. Researchers told farmers at a ‘field day’ at the University’s Northeast Research and Extension Centre that a farmer could follow all regulations at spraying and the herbicide could still move off-target under certain weather conditions, up to 36 hours after application. They also said that summer spraying increases the risk of volatility. Researchers took issue with manufacturers’ suggestions that problems arising in fields across the U.S. are the result of spray operators’s actions and are not down to the new products.

Monsanto, which is on the cusp of a $66bn merger with German chemical giant Bayer, also made headlines in a separate case last week, after lawyers released internal memos which detail company scientists’ involvement in reviewing and editing purportedly independent studies that show Monsanto’s first-generation RoundUp herbicide in a more favourable light. The papers appeared in a special edition of the journal Critical Reviews in Toxicology, which was published following the World Health Organisation’s International Agency for Research on Cancer’s (IARC) assessment that the product’s active ingredient, the off-patent herbicide glyphosate, is “probably” carcinogenic to humans. The UK-based publisher of the journal has said it has mounted its own investigation into the issue.