More than half of US retail sales of corn, cotton and soyabean seeds in 2018-2020 – the most up-to-date estimates available – were supplied by Corteva and Bayer, according to a report by the US Department of Agriculture (USDA)’s Economic Research Service (ERS).

In recent decades, the US crop seed industry had become more concentrated, with fewer and larger firms dominating seed supply, the 2 October report said.

Four companies – Bayer and Corteva along with ChemChina’s Syngenta Group and BASF – currently control the bulk of crop seed and agricultural chemical sales, according to the report.

In 2015, six firms led global markets for seeds and agricultural chemicals.

That market concentration could be traced back to the expansion of intellectual property rights to private companies for seed improvements in the 1970s and 1980s, which created an incentive to research and develop new biotechnology seed traits and seed varieties, the report said.

As biotechnology advanced, companies created genetically modified (GM) varieties of seed, such as herbicide-tolerant or insect-resistant corn, soyabeans and cotton.

Mergers took place among companies that produced and sold pesticides (primarily herbicides, insecticides and fungicides), seed treatments (seed coatings to protect against insects or fungi), crop seeds and seed traits.

As a result, the US crop seed sector had become more concentrated and highly integrated with agricultural chemicals, the report said.