USDA has paved the way for commercial release of two new genetically modified crops intended to combat pests that have grown resistant to currently approved bioengineered crops. One of the new crops is a strain of cotton that is resistant to Dow AgroSciences’ Enlist Duo herbicide, which is a mixture of 2,4-D and glyphosate, and to glufosinate. The other crop is a new strain of corn developed by Monsanto to tolerate corn rootworm and glyphosate. USDA granted preliminary approval for the cotton on May 22, making it the third crop, after corn and soybeans, to be approved for use with Dow’s Enlist Duo. USDA also released favorable assessments of Monsanto’s new corn the same day, making it likely that the agency will approve that crop as well. If approved, Monsanto’s seed would become the first commercial corn that relies on RNA interference, which involves silencing the expression of specific genes in the rootworm. When a rootworm eats the modified corn’s roots, some of the worm’s essential genes are silenced and it dies.