Overly optimistic assumptions about transgenic crops that produce two or more Bt toxins active against the same pest can lead to inadequate strategies for delaying evolution of pest resistance, says University of Arizona.

Slow planting progress this spring has led to all efforts focused on getting the crop in the ground. Often the first operation thrown to the wayside is application of pre-emergence herbicides in soybean. A decade ago this practice could be successful, but with widespread multiple herbicide resistance, it either sets up an imminent control failure or contributes to further evolution of herbicide resistance.

For folks growing continuous corn, western corn rootworm is a serious pest that needs regular attention. Most growers in Pennsylvania seem to be aware of the ongoing struggle in the Midwest with populations of western corn rootworm that are resistant to some varieties of Bt corn.

Corn that contains proteins that protect it from insect damage has been grown in the U.S. since the mid-1990s. Known as Bt corn, because the proteins are derived from a bacterium called Bacillus thuringiensis, these plants have been widely grown by farmers.