In early July, on the sleepy Friday after Independence Day, the USDA quietly signaled its intention to green-light a new genetically engineered soybean seed from Dow AgroSciences. The product is designed to produce soy plants that withstand 2,4-D, a highly toxic herbicide (and, famously, the less toxic component in the notorious Vietnam War-era defoliant Agent Orange).

Readers may remember that during an even-sleepier period-the week between Christmas and the New Year-the USDA made a similar move on Dow’s 2,4-D-ready corn.

If the USDA deregulates the two products-as it has telegraphed its intention to do-Dow will enjoy a massive profit opportunity. Every year, about half of all US farmland is planted in corn and soy. Currently, Dow’s rival Monsanto has a tight grip on weed management in corn-and-soy country. Upward of 90 percent of soy and 70 percent of corn is engineered to withstand another herbicide called glyphosate through highly profitable Monsanto’s Roundup Ready seed lines. And after so many years of lashing so much land with the same herbicide, glyphosate-resistant superweeds are now vexing farmers and ‘alarming’ weed control experts throughout the Midwest.

And that’s where Dow’s 2,4-D-ready corn and soy seeds come in. Dow’s novel products will be engineered to withstand glyphosate […]