Potential rootworm resistance found in IL corn
As if Mother Nature's not done enough damage the last few weeks, Illinois crop specialists are finding "severe" levels of corn rootworm damage in fields of first-year Bt corn with rootworm protection.
The severe damage was discovered in Livingston and Kankakee counties in northeastern Illinois and, according to University of Illinois Extension crop scientist Michael Gray, show farmers may not be properly utilizing current corn rootworm protection products, or those products aren't performing up to snuff. It ultimately carries some ominous implications for the future of rootworm protection, he says..
"Many first-year Bt cornfields in the area had severe root pruning and lodging. The fact that rotated corn is now showing susceptibility to rootworm damage, even when planted to certain Bt hybrids, is evidence that crop rotation in central and east central Illinois does not adequately confer a consistent level of root protection," Gray says. "The number of beetles in the soybean fields was reminiscent of densities in the late 1990′s and early 2000′s — very impressive. The density of western corn rootworm adults in both crops, along with the severe pruning and lodging, was additional evidence that the Bt hybrids had failed to offer the necessary root protection."
Samples from the infected plants will now undergo further analysis in a lab to determine whether or not the western corn rootworm adults are resistant to the Cry3Bb1 protein, one common in current Bt varieties. If resistance is found, that's where the major implications will come in, Gray says.
"If the bioassays confirm resistance to the Cry3Bb1 protein, producers across a wide swath of Illinois will have a formidable insect foe capable of overcoming both crop rotation and at least one Bt protein," he adds.