Iowa Senator Chuck Grassley has written to the U.S. Justice Department asking for close review of the proposed Dow Du Pont Merger. He says he’s concerned at the trend that’s led to consolidation of the seed industry leaving very few players and lessening competition in the marketplace.

He says if all of the proposed seed company mergers are approved it will mean more concentration of the industry and even foreign ownership of one of the major businesses.

Grassley says he wants DOJ to make a thorough and close review of the possible effects of the potential merger.

Shareholders for Dow Chemical and DuPont will be holding separate shareholder meetings soon to vote on the proposed merger between the two companies.