In fields where Bt rootworm corn hybrids have been used for more than three consecutive years, resistance among corn rootworm populations is suspected. Growers can no longer rely solely on Bt hybrids for protection against rootworm injury. The best management practice to reduce the resistant rootworm population is to rotate out of corn for at least one year. Growers are encouraged to replace corn for a minimum of one year, but ideally for the next two to three years. More information on the recommended measures to mitigate the resistant CRW populations are available here: Mitigation Measures for Bt Resistant Corn Rootworm
For livestock producers, rotating out of silage, grain, or high-moisture corn has a large impact on their feed supply. To assist the corn seed sector in supporting their livestock clients, the Canadian Corn Pest Coalition and OMAFRA have provided some two-page documents that offer suggestions of which other crops may be grown to replace corn in rations, and how these crops can be fed. These documents can be used to start conversations about transitioning out of continuous corn and into a crop production system that supports the long-term responsible use of Bt hybrids for rootworm management.
Producers should test feed ingredients and consult a nutritionist to ensure rations are properly balanced.