DuPont and Dow Chemical have won US competition approval to merge on condition that the companies sell certain crop protection products and other assets. 

The asset sales required by US competition enforcers were similar to what the companies had agreed to give up in a deal they struck with European regulators in March. 

The deal is one of several big mergers by farm suppliers, and the antitrust approval was quickly denounced by the head of the National Farmers Union, saying that farmers would face higher costs. 

The US Justice Department said the asset sales would prevent price hikes or lost innovation. 

Dow and DuPont announced the deal in December 2015 in what was billed as an all-stock merger valued at $130 billion. 

According to the filing in US District Court for the District of Columbia, the assets to be sold include DuPont's Finesse herbicide for winter wheat and Rynaxypyr insecticides, which the Justice Department said had US annual sales of more than $100m. 

In addition, Dow will sell its US acid copolymers and ionomers business. The products are used to make food packaging and other goods.

The US Justice Department and Federal Trade Commission, which share the work of competition enforcement, have reviewed or are reviewing no fewer than four deals involving corporate titans that supply US farmers. 

In addition to Dow and DuPont merger deal, Bayer has a deal to buy Monsanto, and ChemChina is purchasing Syngenta. 

Meanwhile, fertilizer companies Potash Corp and Agrium are also planning a merger. 

After Dow completes the merger with DuPont, the companies have said that they would split into three separate companies specializing in material sciences, specialty products, and seeds and agrochemicals.

Dow and DuPont have already received clearance to merge from Europe, China and Brazil. 

They are now awaiting approval from just a handful of countries, including Canada and Mexico.