Freese and other advocates also raised concerns about possible
health risks from increased use of 2,4-D and the chemical's tendency to drift beyond the area where it is sprayed, threatening neighboring crops and wild plants.
Dow AgroSciences has attempted to address that by developing a new version of 2,4-D and new equipment to use with it, company spokesman Garry Hamlin said.
The seeds and new 2,4-D have been approved in Canada but not yet sold there.