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Conclusion  |
Corn Rootworms have shown a remarkable ability to adapt to control measures. Crop rotation is not immune to this either. Two separate examples or cases of resistance to rotation have been discovered in corn rootworms. These two cases are known as the soybean variants and extended diapause. Some corn rootworms that have adapted to lay eggs in fields other than corn such as soybean or any other rotational crop. The next spring when the field is planted to corn the larvae are there to feed on the roots. Previously, the adults wouldn’t lay eggs in places like soybean fields because there were no corn plants to serve as a host for the adults or the larvae the next season. This can pose a serious problem since rotation is the most effective control measure for corn rootworms. Fortunately, this behavior is only found in Western corn rootworms and they are not found in all areas. They are currently found in areas of Michigan, Illinois, Indiana and Ohio. For more information on rotation resistant corn rootworms in your area or management options contact your local extension agent or agronomist for more information.
The other case is known as extended diapause. This is when eggs laid in a cornfield that is planted to soybeans the next spring do not hatch. They will remain in diapause for another year and emerge the next year when it is rotated back to corn. This too can significantly reduce the efficacy of rotation to a non-host crop when controlling for corn rootworm. Extended diapause is only found in Northern corn rootworms in areas of North and South Dakota, Nebraska, Iowa and Minnesota. For more information about them in your area contact you extension agent or agronomist.
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Conclusion |