Friends of the Earth has run a long campaign to try to prevent the takeover, which it warned would “increase control over farmers and cut out competitors, and allow it to become the dominant ‘Facebook of farming’.”

In May, dozens of people demonstrated against the takeover outside Bayer’s AGM in Bonn.

“This merger will create the world’s biggest and most powerful agribusiness corporation, which will try to force its genetically modified seeds and toxic pesticides into our food and countryside,” Bebb said. “The coming together of these two is a marriage made in hell – bad for farmers, bad for consumers and bad for our countryside.”

Bayer won approval for the takeover from US and European regulators after agreeing to sell $9bn worth of assets to reduce the combined companies’ dominance of the global seeds market.

“The acquisition of Monsanto is a strategic milestone in strengthening our portfolio of leading businesses in health and nutrition,” Baumann said. “We will double the size of our agriculture business and create a leading innovation engine in agriculture, positioning us to better serve our customers and unlock the long-term growth potential in the sector.”

Monsanto created dicamba-resistant soybeans (and cotton) in an effort to stay a step ahead of the weeds. The strategy of planting Roundup-resistant crops and spraying Roundup to kill weeds isn’t working so well anymore, because weeds have evolved resistance to glyphosate. Adding genes for dicamba resistance, so the thinking went, would give farmers the option of spraying dicamba as well, which would clear out the weeds that survive glyphosate.

There was just one hitch in the plan. A very big hitch, as it turned out. The Environmental Protection Agency has not yet approved the new dicamba weedkiller that Monsanto created for farmers to spray on its new dicamba-resistant crops. That new formulation of dicamba, according to Monsanto, has been formulated so that it won’t vaporize as easily, and won’t be as likely to harm neighboring crops. If the EPA approves the new weedkiller, it may impose restrictions on how and when the chemical may be used.

But, Monsanto went ahead and started selling its dicamba-resistant soybeans before this herbicide was approved. It gave farmers a new weed-killing tool that they couldn’t legally use.