(Reuters) – An advanced weed-killing chemical has twice come back to haunt Arkansas farmer John Weiss.
The herbicide, known as dicamba, has long been employed in the United States to kill weeds before fields were planted, but its use spiked after regulators last year approved a new formulation that allowed farmers to apply it to growing plants.
That should have been good news for Weiss and hundreds of other farmers, who planned to use it to control hard-to-kill weeds in fields planted with crops bioengineered to survive the chemical.
Instead, farmers reported the agricultural chemical was drifting into neighboring fields and damaging crops unable to resist it. Last month, in response to the reports, Arkansas and Missouri temporarily banned its use.
The fallout from dicamba hit Weiss on two fronts: The drifting chemicals, he said, stunted his unprotected soybean crops and marked the plants with damaged, withered leaves.
Then came the ban, which meant he could no longer use the chemical on the dicamba-resistant soybeans and cotton it was meant to protect.
“It’s just a double whammy, this whole thing,” said Weiss.
Crops have suffered damage across much of the farm belt. Governments in 17 states are investigating more than 1,400 complaints of dicamba problems covering 2.5 million acres, Kevin Bradley, a University of Missouri associate professor in the plant sciences division, wrote last week.
The three companies that sell the chemical in the United States for use on growing crops of soybeans and cotton, Monsanto Co, BASF and DuPont, say their products have not always been used according to label instructions.
Some farmers used older dicamba products that were more drift-prone, deployed spraying equipment contaminated with other herbicides, or applied dicamba in the wrong conditions, Monsanto’s chief technology officer Robb Fraley said.
The situation is part of an evolving battle between farmers and pests that threaten their crops. For two decades, growers have sown crops genetically modified to resist chemicals such as glyphosate, popularly known as Roundup, allowing them to selectively kill all the weeds in a field.
But the weeds have rallied, developing resistance to many popular chemicals, prompting farmers to try alternatives such as dicamba.
It is unclear what is causing dicamba to drift into other crops, though agronomists say it could be caused by high winds or changes in temperature.
Complaints have been rampant. So far,…