By Scout Nelson
Corn rootworms remain a major threat to corn production in Minnesota, with western corn rootworm (WCR) and northern corn rootworm (NCR) capable of causing significant yield losses. Their larvae feed on corn roots, reducing plant health and increasing the risk of lodging and harvest difficulties.
Western corn rootworm beetles are yellow with black markings, while northern corn rootworm beetles are light green. WCR is often associated with continuous corn production, while NCR can move more freely between fields, increasing its potential spread.
Rootworms overwinter as eggs in the soil and hatch in late spring or early summer. The larvae feed on corn roots, damaging the plant's ability to absorb water and nutrients and creating openings for disease infection.
Scouting remains an important part of rootworm management. Growers can monitor beetle populations using plant inspections or yellow sticky traps to assess the risk of future infestations and guide management decisions.
Crop rotation is one of the most effective ways to reduce rootworm pressure because larvae depend on corn roots for survival. However, some rootworm populations have adapted to traditional rotation practices, making additional control strategies necessary.
Bt corn hybrids continue to provide protection against rootworm feeding, although resistance has been identified in some western corn rootworm populations. New technologies, including RNAi-based traits, are expected to expand future management options.
Chemical insecticides are also available, but effectiveness varies depending on pest pressure and product selection. Some organophosphate insecticides have shown strong performance, while seed treatments tend to be less effective against higher rootworm populations.
The University of Minnesota Plant Disease Clinic helps growers diagnose crop diseases and provides management recommendations. Accurate diagnosis can improve disease management and support better crop health decisions.
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Categories: Minnesota, Crops, Corn