Corn rootworm management update
The following options are suggested if you have had higher than expected injury from corn rootworms in your Bt corn field this year:
1. Rotate to a crop other than corn—this is still the best way to reduce corn rootworm populations in Nebraska. Regularly rotating some corn acres can help reduce rootworm densities on a farm. In Nebraska we do not have the “rotation resistant variant” western corn rootworm that has been found in the eastern Corn Belt. It has increased the number of crops in which it will lay eggs to include soybean and other crops, thus reducing the benefit of crop rotation.
2. If you must plant corn after corn:
— Change to a hybrid containing a different Bt corn toxin active against rootworms, or one containing more than one Bt corn toxin active against corn rootworms. See http://www.entomology.wisc.edu/cullenlab/extension/xtras/PDFs/Handy%20Bt%20Trait%20Table.pdffor a list of available Bt corns and the toxins they express.
— Follow all refuge requirements for any Bt hybrid.
3. It is important to use a diversity of control measures to manage rootworm populations, rather than relying on only one Bt corn. Crop rotation and use of different Bt corn hybrids that express different or multiple Bt proteins are important strategies for rootworm management. In addition, conventional insecticides may be used to provide some level of protection as part of a rootworm management program, including the following:
— Neonicotinoid seed treatment (Cruiser, Poncho) at the high rootworm rate
— Liquid or granular insecticide applied at planting
— Postemergence applications targeted for larval or adult control