Researchers at the University of Texas at Austin have developed a chemical that could help farmers cut down on the hundreds of millions of kilograms of herbicide they spray on their fields each year. Plant cells defend themselves from herbicides using proteins that pump invading herbicide molecules out before they have a chance to do harm. The researchers’ chemical, which would be combined with a conventional herbicide, inhibits an enzyme that powers these proteins, slowing the pumps so that the herbicide has more time inside the cells to do its job. In one field test, the herbicide helper reduced by 50 percent the amount of a common herbicide called atrazine needed to keep a corn crop free of weeds. The university has licensed the technology to Entercel, a startup that aims, via partnership with an agricultural chemical company, to have a combination herbicide and booster product on the market within five years.