Forage Options to Replace Silage Corn

Key Points: Some regions in Ontario have observed high corn rootworm pressure in 2020 that is challenging current Bt rootworm hybrids. In regions where Bt rootworm corn hybrids have been used for more than three consecutive years, resistance among corn rootworm populations is suspected. Several growers in Ontario are reporting fields with rootworm injury to trait providers and research and extension scientists. Growers in areas with resistant rootworm populations can no longer rely solely on Bt rootworm hybrids for protection against rootworm injury. Continued use of these hybrids in problem fields can perpetuate the issue, allowing resistant populations to survive and spread to neighbouring fields. Other control measures like granular insecticides or seed treatments can only provide root protection in low to moderate populations; they do not reduce rootworm populations. The best management practice to reduce the resistant rootworm population is to rotate out of corn for at least ...