By now you must have heard that for a few years corn growers in large portions of the Midwest have been battling populations of western corn rootworm that are resistant to YieldGard varieties of Bt corn.

Researchers say they now know what allows some Western corn rootworms to survive crop rotation, a farming practice that once effectively managed the rootworm pests.

Wayne Bailey, University of Missouri Extension specialist in plant sciences, urges Missouri corn producers to keep an eye out for indications of corn rootworm, caused by continuous planting of Bt hybrid corn on cropland.

A new study answers a question that has baffled researchers for more than 15 years: How does the western corn rootworm — an insect that thrives on corn but dies on soybeans — persist in fields that alternate between corn and soybeans?

Federal monitors said this week they have found more evidence that Monsanto's genetically engineered corn is failing to kill the insects it is designed to repel.

An issue facing corn growers this fall and winter when purchasing corn for next summer centers around the recent announcement of western corn rootworms developing resistance to Cry3Bb1.

Following reports of high damage in Iowa, lab studies revealed resistance to Bt hybrids expressing Cry3Bb1 toxin, found in Monsanto hybrids targeting rootworms.

A more practical and economic approach to achieving high yields is to follow proven cultural practices that enhance corn performance.

Bags of corn seed that mix genetically modified hybrids with and without Bt toxins that kill insects provide farmers easier compliance with federal regulations but could, over time, hasten insect resistance to Bt, a Purdue University entomologist said.

Syngenta announced that the U.S. Environmental Protection Agency has granted registration approval for the Agrisure Viptera 3220 trait stack, which offers corn growers dual modes of action against above-ground (lepidopteran) insect pests.